Question

a boy standing behind a 12-foot fence throws a baseball into the air. If the height of the ball above the ground is given by h=-16t^2+48t-20 find the value of t(time in seconds) that the ball is above the fence (h>12)

Answer 1

It stays above the air for around a second. I graphed in Desmos to get this answer. Try doing that, and you will see how I got my answer.

Answer 2

If h=-16t^2+48t-20 and if h>12 you plug >12 into the h position in the equation:
12<-16t^2+48t-20; simplified to: 0<-16(t^2-3t+2)
Then you solve THIS equation by factoring and you should get:
0<(t-1)(t-2). 1<t and 2<t are your t(x) values. So when h(y)>12, t>1 & 2.
I hope this helps. You didn't give any answer choices so I'm not sure how they want the answer to look.