What number would be equal to 9.32 when you increase it by 4.65

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.

If square root x = -7, then x= -49 true or false

How to do this , and can some one explain