Can someone plzzz help

Solve for x, y, and z. show all steps.

Ahovercraft takes off from a platform. its height (in meters), xx seconds after takeoff, is modeled by: h(x)=-2x^2+20x+48h(x)=−2x 2 +20x+48 what is the maximum height that the hovercraft will reach?

When you find the area of a triangle do you use in. or in2