For $0\leq t\leq4$, a ball’s height is modelled by $$H=-5t^2+20t+1,$$ where $H$ is in

Question

For $0\leq t\leq4$, a ball’s height is modelled by $$H=-5t^2+20t+1,$$ where $H$ is in metres and $t$ is in seconds. Express $H$ in completed-square form. Find the maximum height and when it occurs. Find the two times when the ball is $16\text{ m}$ high.

Accepted Answer

(a) $H=-5(t-2)^2+21$; (b) Maximum $21\text{ m}$ at $2\text{ s}$; (c) $H=16$ at $t=1,3\text{ s}$.

Quadratic Functions, Equations and Inequalities

Quadratic Functions, Equations and Inequalities

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