Find d/dx of (x² + 1)³.
Answer and explanation
Correct answer: D. 6x(x² + 1)²
- Step 1: Use the chain rule: the outer power gives 3(x² + 1)². Step 2. Multiply by the derivative of the inner function, 2x. Answer: 6x(x² + 1)². Why not the others: omitting the inner derivative, using x² only, or keeping the power 3 are chain-rule errors.
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