Question

After t seconds a ball thrown in the air from ground level reaches a given

Answer 1

Answer:

9 sec.

Step-by-step explanation:

I think you wrote the equations incorrectly.  It probably is

$h = -16t^{2} + 144t + 100$

If that is true, then $100 = -16t^{2} + 144t + 100$

                                    0 = -16$t^{2}$ + 144t

                                       -16t(t - 9) = 0

                                            t = 0 or t = 9