At what time, t, does the object hit the ground?

s(t)=t^2â4tâ12

Solution = _____ Seconds

For some reason I don't understand how to do it. I've done things just like these Quadratic Functions, but because its t^2-4t-12=s(t) instead of something like t^2-4t-12=0. The two variables is throwing me off horendously.

PLEASE SOMEBODY HELP ME

Guest Feb 16, 2017