If someone throws a ball down from a height of 100 meters, the ball's distance from the ground can be modeled by the equation: d = − 9.8 t 2 − 15 t + 100 where t is the time in seconds and d is the distance in meters.

Question;

At what time (t) will the ball hit the ground?

The answer to the question is;

The ball will hit the ground at t = 2.52 s

Step-by-step explanation:

To answer the question we note the formula for distance from the gound is given by

d = − 9.8·t² − 15·t + 100

To find out the time when the ball hits the ground we have

The ball hits the ground at d = 0, therefore we have

0 = − 9.8·t² − 15·t + 100, solving by factorization gives

(t-2.52)(t+4.05)×(-9.8) = 0

Therefore the ball hits the ground at either 2.52 s or -4.05 s (imaginary)

Which gives t = 2.52 s.