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Derivative of \( \displaystyle \frac{2 x + 5}{x - 3} \)

Problem 2.558 · medium

Differentiate \( \displaystyle f(x) = \frac{2 x + 5}{x - 3} \).
  1. \[ \frac{d}{d x} \frac{2 x + 5}{x - 3} \]
    derivative rewriteStart with the derivative of the function. Rewrite the quotient as a product using a negative exponent.✓ Proved
  2. \[ = \left(2 x + 5\right) \frac{d}{d x} \frac{1}{x - 3} + \frac{\frac{d}{d x} \left(2 x + 5\right)}{x - 3} \]
    productApply the product rule.✓ Proved
  3. \[ = \left(2 x + 5\right) \frac{d}{d x} \frac{1}{x - 3} + \frac{2}{x - 3} \]
    derivativeDifferentiate the first part of the product.✓ Proved
  4. \[ = \frac{\left(- 2 x - 5\right) \frac{d}{d x} \left(x - 3\right)}{\left(x - 3\right)^{2}} + \frac{2}{x - 3} \]
    chainApply the chain rule to the second part.✓ Proved
  5. \[ = \frac{- 2 x - 5}{\left(x - 3\right)^{2}} + \frac{2}{x - 3} \]
    derivativeDifferentiate the inner function (x - 3).✓ Proved
  6. \[ = \frac{2}{x - 3} - \frac{2 x + 5}{\left(x - 3\right)^{2}} \]
    algebraSimplify the expression using exponents.✓ Proved
  7. \[ = - \frac{11}{\left(x - 3\right)^{2}} \]
    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
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x - 3 = 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where x - 3 = 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-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.