Question

Find the first derivative with respect to x of the following function: f(x)=(7x+3)(4-3x)

Answer 1

You have the derivative of a product:

first limit (7x+3)

second limit (4-3x)

The Rule for the derivative of a product is:

(first limit × derivative of second limit) + (second limit × derivative of first limit)

f(x) = (7x+3)(4-3x)

f'(x)=(7x+3)×-3 + (4-3x)×7 = -21x- 9 + 28-21x

f'(x) = -42x + 19