Estimate the line of best fit using two points on the line (4,6) (9,10)

Brent wants to know what is 5 x 1/2

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.

The parabola y = x² - 4 opens: a.) up b.) down c.) right d.) left