Chapter 4 Quadratic Functions and Factoring - 4.8 Use the Quadratic Formula and the Discriminant - 4.8 Exercises - Problem Solving - Page 299: 73c

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When the ball reaches 15: $15=20t\\ \rightarrow t=0.75$ Find y: $y=16t^2+21t+6$ Substitute: $y=16(0.75)^2+21(0.75)+6=12.75$ Thus, the ball passes through $(15,12.75)$. Since $12.75\gt 12$, the ball will pass above the backboard. The player cannot make the free throw.