In order to use cpctc in a proof, what must you first prove?

The chs baseball team was on the field and the batter popped the ball up. the equation b(t)=80t-16•16+3.5 represents the height of the ball above the ground in feet as a function of time in seconds. how long will the catcher have to get in position to catch the ball before it hits the ground? round to the nearest second

If x = -2, then x 2-7x+10 equals a. 0 b.20 c.28

Bring the fraction a/a-4 to a denominator of 16-a^2