F(a) = a^4- 6a² - 10a - 4 at a=-2

Pls , the question is in the picture!

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.

Polynomial that can be factored as (3x-4)(3x+4)