The derivative of a product: (fg)′ = f′g + fg′. 264 problems with worked solutions; in 263 of them every
equation is proved by a computer algebra system.
20 worked problems
Try each one before opening the solution. Every line is labeled with what checked it; 20 of these also have a second solution, written separately and checked the same way. How we verify
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
derivativealgebraDifferentiate log(x). Simplify the term x**2 * (2/x).✓ Proved
\[ = 3 x \ln{\left(x \right)} \]
algebrasimplifysimplifyDistribute 2*x into the parentheses. Combine like terms. Final simplification.✓ Proved
Answer \( 3 x \log{\left(x \right)} \)
Top: the graph of f = 3x²·(2log(x) - 1)/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 3x·(2log(x) - 1)/2 + 3x/2.
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
derivativeDifferentiate the second part of the product.✓ Proved
\[ = e^{x} \sin{\left(x \right)} \]
algebrasimplifysimplifyFactor out exp(x). Combine like terms. Final simplification.✓ Proved
Answer \( e^{x} \sin{\left(x \right)} \)
Top: the graph of f = (sin(x) - cos(x))·e^(x)/2. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (sin(x) - cos(x))·e^(x)/2 + (sin(x) + cos(x))·e^(x)/2.
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
productApply the product rule to the first term.✓ Proved
\[ = 3 x \ln{\left(x \right)} \]
derivativesimplifyconstant-multiplesimplifyDifferentiate the individual components. Simplify the expression inside the parentheses. Distribute the constant 3/2. Combine like terms.✓ Proved
Answer \( 3 x \ln{\left(x \right)} \)
Top: the graph of f = 3x²·log(x)/2 - 3x²/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 3x·log(x).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
powersimplifysimplifysimplifysimplifysimplifysimplifyDifferentiate x**2 and log(x) Simplify x**2*(1/x) to x Factor 3 inside the parentheses Distribute the 3 Combine like terms Cancel the 3*x terms Divide by 2 to get the final derivative✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
productApply the product rule to the first term.✓ Proved
\[ = x \ln{\left(x \right)} \]
derivativealgebraalgebrasimplifyDifferentiate the individual components. Simplify the term x**2/x. Distribute the constant 1/2. Combine like terms.✓ Proved
Answer \( x \ln{\left(x \right)} \)
Top: the graph of f = x²·log(x)/2 - x²/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = x·log(x).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
productApply the product rule to the first term.✓ Proved
\[ = - x \ln{\left(x \right)} \]
derivativealgebraalgebrasimplifyDifferentiate the individual components. Simplify the terms inside the parentheses and the second term. Distribute the constant -1/2. Combine like terms.✓ Proved
Answer \( - x \ln{\left(x \right)} \)
Top: the graph of f = -x²·log(x)/2 + x²/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -x·log(x).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
derivativesimplifyrewritesimplifyRewrite -(2*x*log(x)+x)/2 as -x*log(x)-x/2✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ = 2 x \ln{\left(x \right)} + x - \frac{d}{d x} \frac{x^{2}}{2} \]
logarithmicsimplifyDerivative of log(x) is 1/x Simplify x**2*(1/x) to x✓ Proved
\[ = 2 x \ln{\left(x \right)} + x - \frac{\frac{d}{d x} x^{2}}{2} \]
constant-multipleRewrite derivative of x**2/2✓ Proved
\[ = 2 x \ln{\left(x \right)} \]
powersimplifysimplifyDerivative of x**2 is 2*x Simplify 2*x/2 to x Cancel +x and -x✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Top: the graph of f = x²/2 - x·(x - 1)·log(2x - 1) - x/2 - log(2x - 1)/4. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -2x·(x - 1)/(2x - 1) - x·log(2x - 1) + x - (x - 1)·log(2x - 1) - 1/2 - 1/(2(2x - 1)).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(\frac{x^{2}}{2} - x \left(x - 1\right) \ln{\left(2 x - 1 \right)} - \frac{x}{2} - \frac{\ln{\left(2 x - 1 \right)}}{4}\right) \]
derivative✓ Proved
\[ = - x \left(x - 1\right) \frac{d}{d x} \ln{\left(2 x - 1 \right)} + x - \left(2 x - 1\right) \ln{\left(2 x - 1 \right)} - \frac{\frac{d}{d x} \ln{\left(2 x - 1 \right)}}{4} - \frac{1}{2} \]
product✓ Proved
\[ = - \frac{2 x \left(x - 1\right)}{2 x - 1} + x - \left(2 x - 1\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} - \frac{1}{2 \left(2 x - 1\right)} \]
chain✓ Proved
\[ = - \frac{2 x \left(x - 1\right)}{2 x - 1} + x - \left(2 x - 1\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} - \frac{1}{4 x - 2} \]
simplifyalgebra✓ Proved
\[ = x - \left(2 x - 1\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} - \frac{4 x \left(x - 1\right) + 1}{4 x - 2} \]
simplifyCombined rational terms✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ = - \frac{3 x}{2} + \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) \frac{d}{d x} \ln{\left(3 x - 1 \right)} + \ln{\left(3 x - 1 \right)} \frac{d}{d x} \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) + \frac{1}{2} \]
productApply the product rule to the third term.✓ Proved
\[ = - \frac{3 x}{2} + \left(- \frac{d}{d x} x + \frac{3 \frac{d}{d x} x^{2}}{2}\right) \ln{\left(3 x - 1 \right)} + \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) \frac{d}{d x} \ln{\left(3 x - 1 \right)} + \frac{1}{2} \]
sumDifferentiate the polynomial inside the product rule.✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) \frac{d}{d x} \ln{\left(3 x - 1 \right)} + \frac{1}{2} \]
poweralgebraDifferentiate the power terms in the first part of the product rule. Simplify the expression inside the parentheses.✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \frac{1}{2} + \frac{\left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) \frac{d}{d x} \left(3 x - 1\right)}{3 x - 1} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \frac{1}{2} + \frac{3 \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right)}{3 x - 1} \]
constant-multipleDifferentiate the inner function 3x - 1.✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \frac{1}{2} + \frac{\frac{9 x^{2}}{2} - 3 x + \frac{1}{2}}{3 x - 1} \]
algebrasimplifyalgebraMultiply the 3 into the numerator. Simplify the first two terms. Factor out 1/2 from the numerator.✓ Proved
\[ = \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} \]
algebrasimplifyalgebrasimplifyRecognize the perfect square trinomial. Cancel the common factor (3x - 1). Distribute the 1/2. Combine all terms to find the final simplified derivative.✓ Proved
Answer \( \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} \)
Top: the graph of f = -3x²/4 + x/2 + (3x²/2 - x + 1/6)·log(3x - 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -3x/2 + (3x - 1)·log(3x - 1) + 1/2 + 3(3x²/2 - x + 1/6)/(3x - 1).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ = - \frac{3 x}{2} + \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) \frac{d}{d x} \ln{\left(3 x - 1 \right)} + \ln{\left(3 x - 1 \right)} \frac{d}{d x} \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right) + \frac{1}{2} \]
product✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \frac{1}{2} + \frac{3 \left(\frac{3 x^{2}}{2} - x + \frac{1}{6}\right)}{3 x - 1} \]
derivativesimplify✓ Proved
\[ = - \frac{3 x}{2} + \left(3 x - 1\right) \ln{\left(3 x - 1 \right)} + \frac{1}{2} + \frac{\frac{9 x^{2}}{2} - 3 x + \frac{1}{2}}{3 x - 1} \]
simplifyCombined the fraction✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Top: the graph of f = x²/4 + x/2 - (x²/2 + x + 1/2)·log(x + 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = x/2 - (x + 1)·log(x + 1) + 1/2 - (x²/2 + x + 1/2)/(x + 1).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ \frac{d}{d x} \left(- x^{2} - \frac{x}{2} + \left(2 x^{2} + x + \frac{1}{8}\right) \ln{\left(4 x + 1 \right)}\right) \]
derivativeStart with the derivative of the function.✓ Proved
\[ = - 2 x + \frac{d}{d x} \left(2 x^{2} + x + \frac{1}{8}\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} \]
sumDifferentiate the terms separately.✓ Proved
\[ = - 2 x + \left(2 x^{2} + x + \frac{1}{8}\right) \frac{d}{d x} \ln{\left(4 x + 1 \right)} + \ln{\left(4 x + 1 \right)} \frac{d}{d x} \left(2 x^{2} + x + \frac{1}{8}\right) - \frac{1}{2} \]
productApply the product rule to the second term.✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} + \left(2 x^{2} + x + \frac{1}{8}\right) \frac{d}{d x} \ln{\left(4 x + 1 \right)} - \frac{1}{2} \]
derivativeDifferentiate the polynomial factor.✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{\left(2 x^{2} + x + \frac{1}{8}\right) \frac{d}{d x} \left(4 x + 1\right)}{4 x + 1} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{4 \left(2 x^{2} + x + \frac{1}{8}\right)}{4 x + 1} \]
derivativeDifferentiate the inner function of the logarithm.✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{8 x^{2} + 4 x + \frac{1}{2}}{4 x + 1} \]
algebraalgebraalgebraalgebraalgebrasimplifysimplifySimplify the expression. Distribute the 4 into the numerator. Add and subtract 1/2 to facilitate simplification. Combine terms over a common denominator. Expand the numerator. Simplify the fraction. Remove zero.✓ Proved
\[ = \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} \]
algebraalgebrasimplifyPerform polynomial division on the fraction. Combine the linear terms. Final simplification.✓ Proved
Answer \( \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} \)
Top: the graph of f = -x² - x/2 + (2x² + x + 1/8)·log(4x + 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -2x + (4x + 1)·log(4x + 1) - 1/2 + 4(2x² + x + 1/8)/(4x + 1).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(- x^{2} - \frac{x}{2} + \left(2 x^{2} + x + \frac{1}{8}\right) \ln{\left(4 x + 1 \right)}\right) \]
\[ = - 2 x + \frac{d}{d x} \left(2 x^{2} + x + \frac{1}{8}\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} \]
power✓ Proved
\[ = - 2 x + \left(2 x^{2} + x + \frac{1}{8}\right) \frac{d}{d x} \ln{\left(4 x + 1 \right)} + \ln{\left(4 x + 1 \right)} \frac{d}{d x} \left(2 x^{2} + x + \frac{1}{8}\right) - \frac{1}{2} \]
product✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{\left(2 x^{2} + x + \frac{1}{8}\right) \frac{d}{d x} \left(4 x + 1\right)}{4 x + 1} \]
product✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{4 \left(2 x^{2} + x + \frac{1}{8}\right)}{4 x + 1} \]
chainsimplifyalgebra✓ Proved
\[ = - 2 x + \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} - \frac{1}{2} + \frac{8 x^{2} + 4 x + \frac{1}{2}}{4 x + 1} \]
simplify✓ Proved
\[ = \left(4 x + 1\right) \ln{\left(4 x + 1 \right)} \]
simplifyFraction simplifies to 2*x + 1/2, canceling with -2*x - 1/2✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Differentiate \( \displaystyle f(x) = - \frac{9 x^{2}}{4} - 3 x + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)} \).
\[ \frac{d}{d x} \left(- \frac{9 x^{2}}{4} - 3 x + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)}\right) \]
derivativeStart with the derivative of the function.✓ Proved
\[ = - \frac{d}{d x} 3 x + \frac{d}{d x} \left(- \frac{9 x^{2}}{4}\right) + \frac{d}{d x} \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)} \]
sumApply the sum rule.✓ Proved
\[ = - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + \frac{d}{d x} \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)} \]
constant-multiplePull out the constant -9/4.✓ Proved
\[ = \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \ln{\left(3 x + 2 \right)} + \ln{\left(3 x + 2 \right)} \frac{d}{d x} \left(\frac{9 x^{2}}{2} + 6 x + 2\right) - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} \]
productApply the product rule to the third term.✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} \]
derivativealgebraDifferentiate the polynomial inside the product. Simplify the polynomial derivative.✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + \frac{\left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \left(3 x + 2\right)}{3 x + 2} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + \frac{3 \left(\frac{9 x^{2}}{2} + 6 x + 2\right)}{3 x + 2} \]
derivativeDifferentiate the inner function 3*x + 2.✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + \frac{\frac{27 x^{2}}{2} + 18 x + 6}{3 x + 2} \]
algebraDistribute the 3 into the numerator.✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + \frac{27 x^{2} + 36 x + 12}{6 x + 4} \]
algebraalgebraFind a common denominator for the fraction term. Factor out 3 from the numerator.✓ Proved
\[ = \frac{3 \left(3 x + 2\right)^{2}}{6 x + 4} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} \]
algebraRecognize the perfect square trinomial.✓ Proved
\[ = \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 \frac{d}{d x} x - \frac{9 \frac{d}{d x} x^{2}}{4} + 3 \]
algebraCancel the common factor (3*x + 2).✓ Proved
\[ = \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} \]
derivativealgebrasimplifyEvaluate the remaining derivatives. Distribute and expand the terms. Combine like terms to get the final result.✓ Proved
Answer \( 3 \left(3 x + 2\right) \ln{\left(3 x + 2 \right)} \)
Top: the graph of f = -9x²/4 - 3x + (9x²/2 + 6x + 2)·log(3x + 2). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -9x/2 + (9x + 6)·log(3x + 2) - 3 + 3(9x²/2 + 6x + 2)/(3x + 2).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(- \frac{9 x^{2}}{4} - 3 x + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)}\right) \]
derivative✓ Proved
\[ = - \frac{d}{d x} 3 x - \frac{d}{d x} \frac{9 x^{2}}{4} + \frac{d}{d x} \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \ln{\left(3 x + 2 \right)} \]
\[ = - \frac{9 x}{2} + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \ln{\left(3 x + 2 \right)} + \ln{\left(3 x + 2 \right)} \frac{d}{d x} \left(\frac{9 x^{2}}{2} + 6 x + 2\right) - 3 \]
product✓ Proved
\[ = - \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} + \left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \ln{\left(3 x + 2 \right)} - 3 \]
derivative✓ Proved
\[ = - \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 + \frac{\left(\frac{9 x^{2}}{2} + 6 x + 2\right) \frac{d}{d x} \left(3 x + 2\right)}{3 x + 2} \]
chain✓ Proved
\[ = - \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 + \frac{3 \left(\frac{9 x^{2}}{2} + 6 x + 2\right)}{3 x + 2} \]
derivativesimplify✓ Proved
\[ = - \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 + \frac{\frac{27 x^{2}}{2} + 18 x + 6}{3 x + 2} \]
simplify✓ Proved
\[ = - \frac{9 x}{2} + \left(9 x + 6\right) \ln{\left(3 x + 2 \right)} - 3 + \frac{27 x^{2} + 36 x + 12}{6 x + 4} \]
simplifysimplify✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
constant-multiplesimplifyFactor out the common constant 5. Simplify the coefficient.✓ Proved
\[ = - \frac{\sqrt{2} \left(- \sin{\left(5 x + \frac{\pi}{4} \right)} + \cos{\left(5 x + \frac{\pi}{4} \right)}\right) e^{5 x}}{2} \]
algebraFactor out the exponential term.✓ Proved
\[ = e^{5 x} \sin{\left(5 x \right)} \]
algebraalgebraalgebrasimplifyalgebrasimplifyExpand the cosine and sine of the sum using angle addition identities. Substitute cos(pi/4) = sin(pi/4) = sqrt(2)/2. Distribute the negative sign through the second parentheses. Combine like terms inside the parentheses. Multiply the constants and handle the sign. Simplify the final expression.✓ Proved
Answer \( e^{5 x} \sin{\left(5 x \right)} \)
Top: the graph of f = -sqrt(2)·e^(5x)·cos(5x + pi/4)/10. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = sqrt(2)·e^(5x)·sin(5x + pi/4)/2 - sqrt(2)·e^(5x)·cos(5x + pi/4)/2.
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
derivativealgebraDifferentiate each factor Simplify the minus sign✓ Proved
\[ = - \frac{\sqrt{2} \left(- \sin{\left(5 x + \frac{\pi}{4} \right)} + \cos{\left(5 x + \frac{\pi}{4} \right)}\right) e^{5 x}}{2} \]
algebraconstant-multiplesimplifyFactor out common terms Combine constants Reduce the fraction✓ Proved
\[ = \frac{\sqrt{2} e^{5 x} \sin{\left(5 x + \frac{\pi}{4} \right)}}{2} - \frac{\sqrt{2} e^{5 x} \cos{\left(5 x + \frac{\pi}{4} \right)}}{2} \]
algebraDistribute the factor✓ Proved
\[ = \frac{\sqrt{2} \left(\sin{\left(5 x + \frac{\pi}{4} \right)} - \cos{\left(5 x + \frac{\pi}{4} \right)}\right) e^{5 x}}{2} \]
simplifyReorder terms✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
productApply the product rule to the third term.✓ Proved
\[ = \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \left(2 x^{2} - 3 x + \frac{9}{8}\right) \frac{d}{d x} \ln{\left(4 x - 3 \right)} + \frac{d}{d x} \frac{3 x}{2} + \frac{d}{d x} \left(- x^{2}\right) \]
poweralgebraDifferentiate the polynomial part. Simplify the polynomial derivative.✓ Proved
\[ = \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{d}{d x} \frac{3 x}{2} + \frac{d}{d x} \left(- x^{2}\right) + \frac{\left(2 x^{2} - 3 x + \frac{9}{8}\right) \frac{d}{d x} \left(4 x - 3\right)}{4 x - 3} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{d}{d x} \frac{3 x}{2} + \frac{d}{d x} \left(- x^{2}\right) + \frac{4 \left(2 x^{2} - 3 x + \frac{9}{8}\right)}{4 x - 3} \]
derivativeDifferentiate the inner function of the logarithm.✓ Proved
\[ = \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{d}{d x} \frac{3 x}{2} + \frac{d}{d x} \left(- x^{2}\right) + \frac{8 x^{2} - 12 x + \frac{9}{2}}{4 x - 3} \]
algebraMultiply the constant 4 into the numerator.✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} + \frac{8 x^{2} - 12 x + \frac{9}{2}}{4 x - 3} \]
derivativeEvaluate the remaining derivatives.✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} + \frac{16 x^{2} - 24 x + 9}{8 x - 6} \]
algebraalgebraSimplify the fraction by multiplying numerator and denominator by 2. Distribute the 2 in the denominator.✓ Proved
\[ = - 2 x + \frac{\left(4 x - 3\right)^{2}}{8 x - 6} + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} \]
algebraNotice that the numerator is a perfect square.✓ Proved
\[ = \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} \]
simplifyalgebrasimplifySimplify the fraction by canceling common terms. Combine the rational terms. The linear terms cancel out.✓ Proved
Answer \( \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} \)
Top: the graph of f = -x² + 3x/2 + (2x² - 3x + 9/8)·log(4x - 3). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = -2x + (4x - 3)·log(4x - 3) + 3/2 + 4(2x² - 3x + 9/8)/(4x - 3).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ = - 2 x + \frac{d}{d x} \left(2 x^{2} - 3 x + \frac{9}{8}\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} \]
power✓ Proved
\[ = - 2 x + \left(2 x^{2} - 3 x + \frac{9}{8}\right) \frac{d}{d x} \ln{\left(4 x - 3 \right)} + \ln{\left(4 x - 3 \right)} \frac{d}{d x} \left(2 x^{2} - 3 x + \frac{9}{8}\right) + \frac{3}{2} \]
product✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \left(2 x^{2} - 3 x + \frac{9}{8}\right) \frac{d}{d x} \ln{\left(4 x - 3 \right)} + \frac{3}{2} \]
derivative✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} + \frac{\left(2 x^{2} - 3 x + \frac{9}{8}\right) \frac{d}{d x} \left(4 x - 3\right)}{4 x - 3} \]
chain✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} + \frac{4 \left(2 x^{2} - 3 x + \frac{9}{8}\right)}{4 x - 3} \]
derivativesimplify✓ Proved
\[ = - 2 x + \left(4 x - 3\right) \ln{\left(4 x - 3 \right)} + \frac{3}{2} + \frac{8 x^{2} - 12 x + \frac{9}{2}}{4 x - 3} \]
simplifyfinal simplified derivative✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Top: the graph of f = x²/2 - x/2 + (-x² + x - 1/4)·log(2x - 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = x + (1 - 2x)·log(2x - 1) - 1/2 + 2(-x² + x - 1/4)/(2x - 1).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(\frac{x^{2}}{2} - \frac{x}{2} + \left(- x^{2} + x - \frac{1}{4}\right) \ln{\left(2 x - 1 \right)}\right) \]
derivativeStart with the derivative of the whole function✓ Proved
\[ = x + \frac{d}{d x} \left(- x^{2} + x - \frac{1}{4}\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} \]
derivativeDifferentiate the simple terms✓ Proved
\[ = x + \left(- x^{2} + x - \frac{1}{4}\right) \frac{d}{d x} \ln{\left(2 x - 1 \right)} + \ln{\left(2 x - 1 \right)} \frac{d}{d x} \left(- x^{2} + x - \frac{1}{4}\right) - \frac{1}{2} \]
productApply product rule to the remaining product✓ Proved
\[ = x + \left(1 - 2 x\right) \ln{\left(2 x - 1 \right)} + \left(- x^{2} + x - \frac{1}{4}\right) \frac{d}{d x} \ln{\left(2 x - 1 \right)} - \frac{1}{2} \]
derivativeDifferentiate the first factor✓ Proved
\[ = x + \left(1 - 2 x\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} + \frac{\left(- x^{2} + x - \frac{1}{4}\right) \frac{d}{d x} \left(2 x - 1\right)}{2 x - 1} \]
chainDifferentiate the logarithm✓ Proved
\[ = x + \left(1 - 2 x\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} + \frac{2 \left(- x^{2} + x - \frac{1}{4}\right)}{2 x - 1} \]
derivativesimplifyDifferentiate the inner linear function Simplify the constant factor✓ Proved
\[ = x + \left(1 - 2 x\right) \ln{\left(2 x - 1 \right)} - \frac{1}{2} + \frac{- 2 x^{2} + 2 x - \frac{1}{2}}{2 x - 1} \]
simplifyCombine the fraction into a single rational expression✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
productApply the product rule to the third term.✓ Proved
\[ = 2 x \ln{\left(x \right)} + 2 x \ln{\left(2 \right)} \]
derivativealgebraalgebrasimplifyDifferentiate the components of the product rule. Simplify the term x**2/x. Distribute the terms. Combine like terms.✓ Proved
\[ = 2 x \left(\ln{\left(x \right)} + \ln{\left(2 \right)}\right) \]
simplifyFactor out 2*x.✓ Proved
\[ = 2 x \ln{\left(2 x \right)} \]
simplifyCombine the logarithms.✓ Proved
Answer \( 2 x \ln{\left(2 x \right)} \)
Top: the graph of f = -x²/2 + log((2x)^(x²)). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 2x·log(2x).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ = - x + \frac{d}{d x} x^{2} \ln{\left(2 x \right)} \]
derivative✓ Proved
\[ = x^{2} \frac{d}{d x} \ln{\left(2 x \right)} + 2 x \ln{\left(2 x \right)} - x \]
product✓ Proved
\[ = 2 x \ln{\left(2 x \right)} \]
derivativesimplify✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
algebrasimplifyalgebraalgebrasimplifyFactor the quadratic expression. Cancel the common factor (x - 3). Distribute the -0.5. Rewrite 0.5*x and 1.5 as fractions. Combine all terms to find the final simplified derivative.✓ Proved
Top: the graph of f = x²/4 - 3x/2 + (-x²/2 + 3x - 9/2)·log(x - 3). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = x/2 + (3 - x)·log(x - 3) - 3/2 + (-x²/2 + 3x - 9/2)/(x - 3).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
simplifysimplifysimplifySimplify the fraction by polynomial division Combine like terms Final simplified derivative✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
simplifyThe expression is already in a standard form, but let's combine terms if possible. Actually, let's use the identity cos(a) - sin(a) = sqrt(2)cos(a + pi/4).✓ Proved
\[ = 3 e^{x - 1} \sin{\left(x - 1 \right)} \]
algebraalgebrasimplifytrigsimplifyUse the identity cos(u) - sin(u) = sqrt(2)cos(u + pi/4). Simplify the argument inside the cosine. Multiply the constants: (sqrt(2)*sqrt(2))/2 = 1. Use the identity cos(u + pi/2) = -sin(u). Simplify the final expression.✓ Proved
Top: the graph of f = -3sqrt(2)·e^(x - 1)·cos(x - 1 + pi/4)/2. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 3sqrt(2)·e^(x - 1)·sin(x - 1 + pi/4)/2 - 3sqrt(2)·e^(x - 1)·cos(x - 1 + pi/4)/2.
A second solution, written separately
By qwen3.6:35b-mlx, without seeing the first. SymPy checked every line.
algebraFactor out the common term exp(x-1).✓ Proved
\[ = 3 e^{x - 1} \sin{\left(x - 1 \right)} \]
trigsimplifySimplify the trigonometric expression cos(A-pi/4)-sin(A-pi/4) where A=x-1 using angle sum identities. Multiply the constants: (-3*sqrt(2)/2) * (-sqrt(2)) = 3.✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ = x^{2} \frac{d}{d x} \left(2 \ln{\left(2 x \right)} - 1\right) + 2 x \left(2 \ln{\left(2 x \right)} - 1\right) \]
powerDifferentiate the first part of the product.✓ Proved
\[ = x^{2} \left(- \frac{d}{d x} 1 + \frac{d}{d x} 2 \ln{\left(2 x \right)}\right) + 2 x \left(2 \ln{\left(2 x \right)} - 1\right) \]
sumApply the sum rule to the second part.✓ Proved
\[ = 2 x^{2} \frac{d}{d x} \ln{\left(2 x \right)} + 2 x \left(2 \ln{\left(2 x \right)} - 1\right) \]
constantconstant-multipleDifferentiate the constant term. Factor out the constant 2.✓ Proved
\[ = 2 x \left(2 \ln{\left(2 x \right)} - 1\right) + x \frac{d}{d x} 2 x \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = 2 x \left(2 \ln{\left(2 x \right)} - 1\right) + 2 x \]
derivativealgebraalgebraDifferentiate the inner function 2*x. Simplify the expression inside the parentheses. Simplify the second term.✓ Proved
\[ = 4 x \ln{\left(2 x \right)} \]
algebraalgebraalgebraFactor out 2*x. Simplify the expression inside the parentheses. Final simplification.✓ Proved
Answer \( 4 x \log{\left(2 x \right)} \)
Top: the graph of f = x²·(2log(2x) - 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 2x·(2log(2x) - 1) + 2x.
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ = x^{2} \frac{d}{d x} \left(2 \ln{\left(2 x \right)} - 1\right) + 2 x \left(2 \ln{\left(2 x \right)} - 1\right) \]
derivative✓ Proved
\[ = 2 x^{2} \frac{d}{d x} \ln{\left(2 x \right)} + 2 x \left(2 \ln{\left(2 x \right)} - 1\right) \]
constant-multiple✓ Proved
\[ = 2 x \left(2 \ln{\left(2 x \right)} - 1\right) + x \frac{d}{d x} 2 x \]
chain✓ Proved
\[ = 2 x \left(2 \ln{\left(2 x \right)} - 1\right) + 2 x \]
derivativesimplifysimplify✓ Proved
\[ = 4 x \ln{\left(2 x \right)} \]
simplifysimplifysimplify✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
\[ = x^{2} \frac{d}{d x} \left(2 \ln{\left(4 x \right)} - 1\right) + 2 x \left(2 \ln{\left(4 x \right)} - 1\right) \]
derivativeDifferentiate the first part of the product.✓ Proved
\[ = x^{2} \left(- \frac{d}{d x} 1 + \frac{d}{d x} 2 \ln{\left(4 x \right)}\right) + 2 x \left(2 \ln{\left(4 x \right)} - 1\right) \]
sumDistribute the derivative over the subtraction.✓ Proved
\[ = 2 x^{2} \frac{d}{d x} \ln{\left(4 x \right)} + 2 x \left(2 \ln{\left(4 x \right)} - 1\right) \]
derivativeDifferentiate the terms inside the parentheses.✓ Proved
\[ = 2 x \left(2 \ln{\left(4 x \right)} - 1\right) + \frac{x \frac{d}{d x} 4 x}{2} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = 2 x \left(2 \ln{\left(4 x \right)} - 1\right) + 2 x \]
derivativealgebraalgebraalgebraDifferentiate the inner function 4*x. Simplify the fraction. Simplify the expression. Simplify the second term.✓ Proved
\[ = 4 x \ln{\left(4 x \right)} \]
algebraalgebraalgebraFactor out 2*x. Simplify the expression inside the parentheses. Multiply the terms together.✓ Proved
Answer \( 4 x \ln{\left(4 x \right)} \)
Top: the graph of f = x²·(2log(4x) - 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 2x·(2log(4x) - 1) + 2x.
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ = 2 x \left(2 \ln{\left(4 x \right)} - 1\right) + 2 x \]
productsimplifysimplifyApply product rule Simplify the derivative of log(4*x) Simplify x**2*(2/x)✓ Proved
\[ = 4 x \ln{\left(4 x \right)} \]
simplifysimplifyCombine terms Final simplified derivative✓ Proved
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify