Why it is not possible to draw a square that is not a parallelogram

Which math sentence can be used to determine if the triangle is a right triangle?

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.

What is the value of x in the equation (2)3) (x+6)= -18 a. -36 b. -33 c. -24 d. -18