MediumMathematicsHigh School (11–12)Functions and Calculus › Graphs of FunctionsNumericalBoard Exam SAT

A ball is thrown straight up. After t seconds its height is h = 30t - 5t² metres.

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A ball is thrown straight up. After $t$ seconds its height is $h = 30t - 5t^2$ metres. When is the ball highest, how high does it go, and when does it come back to the ground?

Need a reminder? The key ideaShow

$y = ax^2 + bx + c$ has its vertex at $x = -\dfrac{b}{2a}$ and opens upward when $a > 0$ . Completing the square, $a(x - h)^2 + k$ , gives the vertex $(h, k)$ and the range.

The worked solution

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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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A ball is thrown straight up. After t seconds its height is h = 30t - 5t² metres.

The worked solution

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