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AssignmentMultiple Choice

Differentiation Rules

Question 1 • AP Calculus AB - MA5186 A

Using the product rule, calculate the derivative of f(x) = (9x3 – 2)(x + 3). What is f ′(x)?

Answer
A
36x3 + 81x2 – 2
B
162x5 – 35x2 + 3x
C
162x5 – 36x2 + x + 3
D
9x4 + 18x3 + 54x2 + 2x

Explanation

Use the product rule: if f(x) = u(x)v(x), then f′(x) = u′(x)v(x) + u(x)v′(x). For u(x) = 9x³ − 2 and v(x) = x + 3, this gives f′(x) = 27x²(x + 3) + (9x³ − 2)(1). Expanding and combining terms gives 36x³ + 81x² − 2, which is choice A.

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