# Chapter 9 - Quadratic Functions and Equations - 9-1 Quadratic Graphs and Their Properties - Practice and Problem-Solving Exercises - Page 539: 40

Time is 3.1 seconds

#### Work Step by Step

$h = -16t^{2} + 154$ The apple hits the ground so the height equals 0 so we plug in 0 for h and find t $0 = -16t^{2} + 154$ Subtract 154 from both sides $0 - 154 = -16t^{2} + 154 - 154$ $-154 = -16t^{2}$ Divide -16 on both sides $\frac{-154}{-16}= \frac{-16t}{-16}^{2}$ 9.625 = $t^{2}$ We take square root of both sides $\sqrt 9.625 = \sqrt t^{2}$ $\sqrt 9.625$ = 3.1 x 3.1 t= 3.1

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