The height, h, in meters, of a football t seconds after being thrown is given by the formula: $h = 30t - 5t^2$ . How long after being thrown is the ball at a height of 25 meters?

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Answer 1 · 2017-11-24T21:32:38

Replace h with 25m.

$25 = 30t - 5t^2$

Rearrange it

$-5t^2 + 30t -25 = 0$

Facotorization and Simplification

$-5 ( t^2 -6t + 5) = 5(t-5)(t-1)$

Find t

$(t-5)=0, t = 5$
$(t-1)=0, t = 1$

Has a height of 25 at 1 s and 5 s

The height, h, in meters, of a football t seconds after being thrown is given by the formula: h = 30t - 5t^2h = 30t - 5t^2. How long after being thrown is the ball at a height of 25 meters?