Which ordered pairs are in the solution set of the system of linear inequalities?

Find an equation (in term of x) of line through the points (-1,3) and (1,4)

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 approximate difference in tenths between √12 and √15?