Differentiate y = (3x - 1)^2 and evaluate dy/dx at x = 1.
Answer and explanation
Correct answer: C. 12
- Step 1: Apply the chain rule: dy/dx = 2 x 3 x (3x - 1)^1.
- Step 2: At x = 1 the inner expression equals 2.
- Step 3: dy/dx = 2 x 3 x 2^1 = 12.
Answer
12.
Why not the others: '4' omits the inner derivative 3 from the chain rule; '24' does not lower the exponent by one; '6' forgets to bring down the exponent 2.
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