Chapter 6 - Section 6.7 - Quadratic Equations and Problem Solving - Exercise Set - Page 467: 36

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$h=-16t^2+961$ $0=-16t^2+961$ $0*-1=(-16t^2+961)*-1$ $0=16t^2-961$ $0=(4t+31)(4t-31)$ $4t+31=0$ $4t=-31$ $4t/4=-31/4$ $t=-31/4$ (invalid since we can't have a negative time) $4t-31=0$ $4t=31$ $4t/4=31/4$ $t=31/4$