Differentiate y = (2x + 2)^2 and evaluate dy/dx at x = 2.
Answer and explanation
Correct answer: B. 24
- Step 1: Apply the chain rule: dy/dx = 2 x 2 x (2x + 2)^1.
- Step 2: At x = 2 the inner expression equals 6.
- Step 3: dy/dx = 2 x 2 x 6^1 = 24.
Answer
24.
Why not the others: '12' omits the inner derivative 2 from the chain rule; '36' evaluates y instead of dy/dx; '144' does not lower the exponent by one.
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