Functions like xˣ, with the variable in the base and the exponent: take logs first. 50 problems with worked solutions; in 23 of them every
equation is proved by a computer algebra system.
13 worked problems
Try each one before opening the solution. Every line is labeled with what checked it; 13 of these also have a second solution, written separately and checked the same way. How we verify
Differentiate \( \displaystyle f(x) = \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \).
\[ \frac{d}{d x} \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \]
Start with the derivative of the function.✓ Proved
\[ = \frac{d}{d x} e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
rewriteRewrite the function using the exponential and logarithm form.✓ Proved
\[ = e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \frac{d}{d x} \left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} \]
chainApply the chain rule for the exponential function.✓ Proved
\[ = \left(\left(5 x + 1\right) \frac{d}{d x} \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} + \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} \frac{d}{d x} \left(5 x + 1\right)\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
productApply the product rule to the exponent.✓ Proved
\[ = \left(\left(5 x + 1\right) \frac{d}{d x} \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
derivativeDifferentiate the first part of the product.✓ Proved
\[ = \left(\frac{\left(5 x + 1\right) \frac{d}{d x} \left(\left(5 x + 1\right)^{2} + 1\right)}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
chainApply the chain rule to the logarithm.✓ Proved
\[ = \left(\frac{\left(5 x + 1\right) \left(50 x + 10\right)}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
derivativederivativeDifferentiate the inner function of the logarithm. Differentiate the inner function of the power.✓ Proved
\[ = \left(\frac{10 \left(5 x + 1\right)^{2}}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
algebraSimplify the expression inside the parentheses.✓ Proved
\[ = \left(\frac{10 \left(5 x + 1\right)^{2}}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \]
simplifyConvert the exponential form back to the original base.✓ Proved
Answer \( 5 \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x} \left(2 \left(5 x + 1\right)^{2} + \left(\left(5 x + 1\right)^{2} + 1\right) \log{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) \)
Top: the graph of f = ((5x + 1)² + 1)^(5x + 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = ((5x + 1)·(50x + 10)/((5x + 1)² + 1) + 5log((5x + 1)² + 1))·((5x + 1)² + 1)^(5x + 1).
A second solution, written separately
By qwen3.6:35b-mlx, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \]
derivativeStart by defining the derivative of the given function.Not checked
\[ = \frac{d}{d x} e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
rewriteRewrite the base-exponent form using exp and log to handle differentiation.✓ Proved
\[ = e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \frac{d}{d x} \left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} \]
chainApply the chain rule: derivative of exp(u) is exp(u)*u'.✓ Proved
\[ = \left(\left(5 x + 1\right) \frac{d}{d x} \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} + \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} \frac{d}{d x} \left(5 x + 1\right)\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
productApply the product rule to the exponent term u = (5x+1)log(...).✓ Proved
\[ = \left(\left(5 x + 1\right) \frac{d}{d x} \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
derivativeCompute the derivative of the linear term 5x+1.✓ Proved
\[ = \left(\frac{\left(5 x + 1\right) \frac{d}{d x} \left(\left(5 x + 1\right)^{2} + 1\right)}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
chainApply the chain rule for the logarithmic term: derivative of log(v) is v'/v.✓ Proved
\[ = \left(\frac{\left(5 x + 1\right) \left(50 x + 10\right)}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
chainApply the chain rule to the quadratic term inside the log.✓ Proved
\[ = \left(\frac{10 \left(5 x + 1\right)^{2}}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) e^{\left(5 x + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}} \]
algebraalgebraSimplify the constant multiplication in the derivative of the quadratic. Combine the terms in the numerator of the fraction.✓ Proved
\[ = \left(\frac{10 \left(5 x + 1\right)^{2}}{\left(5 x + 1\right)^{2} + 1} + 5 \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \]
rewriteRewrite exp(log(...)) back to the original base form.✓ Proved
\[ = \frac{\left(\left(5 x + 1\right)^{2} + 1\right)^{5 x + 1} \left(10 \left(5 x + 1\right)^{2} + 5 \left(\left(5 x + 1\right)^{2} + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right)}{\left(5 x + 1\right)^{2} + 1} \]
algebraFind a common denominator for the terms inside the parentheses.✓ Proved
\[ = \left(\left(5 x + 1\right)^{2} + 1\right)^{5 x} \left(10 \left(5 x + 1\right)^{2} + 5 \left(\left(5 x + 1\right)^{2} + 1\right) \ln{\left(\left(5 x + 1\right)^{2} + 1 \right)}\right) \]
algebraSimplify the power by canceling one factor of the base with the denominator.✓ 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 + 1)^x. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (x² + 1)^x·(2x²/(x² + 1) + log(x² + 1)).
A second solution, written separately
By qwen3.6:35b-mlx, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(x^{2} + 1\right)^{x} \]
derivativeStart with the derivative of the given function.Not checked
rewriteRewrite exp(x * log(x^2 + 1)) back to (x^2 + 1)^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 = ((x - 3)² + 1)^(x - 3). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = ((x - 3)·(2x - 6)/((x - 3)² + 1) + log((x - 3)² + 1))·((x - 3)² + 1)^(x - 3).
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
Top: the graph of f = ((x + 2)² + 1)^(x + 2). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = ((x + 2)·(2x + 4)/((x + 2)² + 1) + log((x + 2)² + 1))·((x + 2)² + 1)^(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
sumApply the sum rule to differentiate each term in the polynomial.✓ Proved
\[ = \left(2 x - 6\right) e^{\left(x - 3\right)^{2}} \]
powersimplifyDifferentiate x^2 to get 2x, -6x to get -6, and the constant 9 to get 0. Simplify the expression inside the parentheses by removing the zero term.✓ 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
✓ 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
derivativeStart with the derivative of the function.✓ Proved
\[ = e^{16 x^{2}} \frac{d}{d x} 16 x^{2} \]
chainApply the chain rule.✓ Proved
\[ = 16 e^{16 x^{2}} \frac{d}{d x} x^{2} \]
constant-multiplePull out the constant factor.✓ Proved
\[ = 32 x e^{16 x^{2}} \]
powersimplifyDifferentiate the power function. Multiply the terms to get the final result.✓ Proved
Answer \( 32 x e^{16 x^{2}} \)
Top: the graph of f = e^(16x²). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 32x·e^(16x²).
A second solution, written separately
By qwen3.6:35b-mlx, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} e^{16 x^{2}} \]
derivativeStart by identifying the function to differentiate.Not checked
\[ = e^{16 x^{2}} \frac{d}{d x} 16 x^{2} \]
chainApply the chain rule: the derivative of exp(u) is exp(u) * u'.✓ Proved
\[ = 32 x e^{16 x^{2}} \]
poweralgebraDifferentiate the inner function 16*x^2 using the power rule. Rearrange the terms for the final simplified answer.✓ 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
derivativeStart with the derivative of the function.✓ Proved
\[ = e^{x^{2}} \frac{d}{d x} x^{2} \]
chainApply the chain rule.✓ Proved
\[ = 2 x e^{x^{2}} \]
derivativealgebraDifferentiate the inner function x**2. Rearrange the terms for the final answer.✓ Proved
Answer \( 2 x e^{x^{2}} \)
Top: the graph of f = e^(x²). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = 2x·e^(x²).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} e^{x^{2}} \]
derivative✓ Proved
\[ = e^{x^{2}} \frac{d}{d x} x^{2} \]
chain✓ Proved
\[ = 2 x e^{x^{2}} \]
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
Top: the graph of f = x^(x - 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = x^(x - 1)·(log(x) + (x - 1)/x).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
simplifySimplify the fraction (x-1)/x to 1-1/x.✓ Proved
✓ Nihil obstat Lines: 8 proved, 2 checked numerically. 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
derivativeStart with the derivative of the function.✓ Proved
\[ = \frac{d}{d x} e^{2 x \ln{\left(2 x + 1 \right)}} \]
rewriteRewrite the base and exponent using the exponential and logarithm.≈ Checked numerically
\[ = e^{2 x \ln{\left(2 x + 1 \right)}} \frac{d}{d x} 2 x \ln{\left(2 x + 1 \right)} \]
chainApply the chain rule for the exponential function.✓ Proved
\[ = \left(2 x \frac{d}{d x} \ln{\left(2 x + 1 \right)} + \ln{\left(2 x + 1 \right)} \frac{d}{d x} 2 x\right) e^{2 x \ln{\left(2 x + 1 \right)}} \]
productApply the product rule to the inner expression.✓ Proved
\[ = \left(2 x \frac{d}{d x} \ln{\left(2 x + 1 \right)} + 2 \ln{\left(2 x + 1 \right)}\right) e^{2 x \ln{\left(2 x + 1 \right)}} \]
derivativeDifferentiate 2*x.✓ Proved
\[ = \left(\frac{2 x \frac{d}{d x} \left(2 x + 1\right)}{2 x + 1} + 2 \ln{\left(2 x + 1 \right)}\right) e^{2 x \ln{\left(2 x + 1 \right)}} \]
derivativeDifferentiate the logarithm using the chain rule.✓ Proved
\[ = \left(\frac{4 x}{2 x + 1} + 2 \ln{\left(2 x + 1 \right)}\right) e^{2 x \ln{\left(2 x + 1 \right)}} \]
derivativealgebraDifferentiate 2*x + 1. Simplify the expression inside the parentheses.✓ Proved
\[ = \left(2 x + 1\right)^{2 x} \left(\frac{4 x}{2 x + 1} + 2 \ln{\left(2 x + 1 \right)}\right) \]
simplifyConvert the exponential form back to the original power form.≈ Checked numerically
Answer \( \left(2 x + 1\right)^{2 x} \left(\frac{4 x}{2 x + 1} + 2 \log{\left(2 x + 1 \right)}\right) \)
Top: the graph of f = (2x + 1)^(2x). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (2x + 1)^(2x)·(4x/(2x + 1) + 2log(2x + 1)).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
\[ \frac{d}{d x} \left(2 x + 1\right)^{2 x} \]
derivative✓ Proved
\[ = \left(2 x + 1\right)^{2 x} \left(\frac{4 x}{2 x + 1} + 2 \ln{\left(2 x + 1 \right)}\right) \]
powerApply the general power rule for a(x)**b(x).✓ Proved
✓ Nihil obstat Lines: 8 proved, 2 checked numerically. 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 = (x + 2)^(x + 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (x + 2)^(x + 1)·((x + 1)/(x + 2) + log(x + 2)).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
powersimplifysimplifyApply the general power rule for a^b Differentiate the exponents and base: (x+1)'=1, (x+2)'=1 Combine constants and simplify the fraction✓ Proved
✓ Nihil obstat Lines: 7 proved, 2 checked numerically. 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 = (x + 1)^x. A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (x + 1)^x·(x/(x + 1) + log(x + 1)).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
derivativesimplifyDifferentiate x and log(x+1) Simplify the expression✓ Proved
✓ Nihil obstat Lines: 7 proved, 2 checked numerically. 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 = (x + 1)^(x + 1). A tangent line slides along it, and its slope is plotted below as it goes, tracing f' = (x + 1)^(x + 1)·(log(x + 1) + 1).
A second solution, written separately
By gpt-oss:20b, without seeing the first. SymPy checked every line.
✓ Nihil obstat Lines: 7 proved, 2 checked numerically. 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