Chapter 4 Quadratic Functions and Factoring - Standardized Test Practice - Extended Response - Page 327: 22c

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We let $h=0$, then $-16t^2+30t+6=0$ Find $t$: $t=\frac{-b \pm \sqrt b^2-4ac}{2a}=\frac{-15 \pm \sqrt 15^2-4(-8)(3)}{2(-8)}=\frac{-15 \pm \sqrt 321}{-16}$ Then, $t=\frac{15+\sqrt 321}{16}\approx 2.057 $ and $t=\frac{15-\sqrt 321}{16}\approx -0.182$ Since the time value cannot be negative, we will choose the positive one: $2.057$ seconds.