## Intermediate Algebra (6th Edition)

We are given in Example 5 that the height of an object at t seconds can be found by the equation $P(t)=-16t^{2}+1125$. To find how long it takes before the object hits the ground, we must find the time t, such that $P(t)=0$. $P(t)=-16(t^{2})+1125=0$ $0=-16t^{2}+1125$ Add $-16t^{2}$ to both sides. $16t^{2}=1125$ Divide both sides by 16. $t^{2}=70.3125$ Take the square root of both sides. $t=8.385\approx8$ seconds