Derivative of \( \displaystyle \frac{2 x + 5}{x - 3} \)
Problem 2.558 · medium
Differentiate \( \displaystyle f(x) = \frac{2 x + 5}{x - 3} \).
- \[ \frac{d}{d x} \frac{2 x + 5}{x - 3} \]derivative rewriteStart with the derivative of the function. Rewrite the quotient as a product using a negative exponent.✓ Proved
- \[ = \left(2 x + 5\right) \frac{d}{d x} \frac{1}{x - 3} + \frac{\frac{d}{d x} \left(2 x + 5\right)}{x - 3} \]productApply the product rule.✓ Proved
- \[ = \left(2 x + 5\right) \frac{d}{d x} \frac{1}{x - 3} + \frac{2}{x - 3} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = \frac{\left(- 2 x - 5\right) \frac{d}{d x} \left(x - 3\right)}{\left(x - 3\right)^{2}} + \frac{2}{x - 3} \]chainApply the chain rule to the second part.✓ Proved
- \[ = \frac{- 2 x - 5}{\left(x - 3\right)^{2}} + \frac{2}{x - 3} \]derivativeDifferentiate the inner function (x - 3).✓ Proved
- \[ = \frac{2}{x - 3} - \frac{2 x + 5}{\left(x - 3\right)^{2}} \]algebraSimplify the expression using exponents.✓ Proved
- \[ = - \frac{11}{\left(x - 3\right)^{2}} \]algebra algebra simplifyFind a common denominator. Distribute the negative sign in the numerator. Combine like terms to get the final answer.✓ Proved
Answer \( - \frac{11}{\left(x - 3\right)^{2}} \)
✓ 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
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 undefined where x - 3 = 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21
Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate
method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence,
not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by
gemma4:26b, checked 2026-09-26 with SymPy 1.14.0.