Question

H=2+25t-5t^2
Find all values for t for which the ball height is 12 meters

Answer 1

`t=(5-√(17))/(2),\:t=(5+√(17))/(2)`

`t=0.43845\dots ,\:t=4.56155\dots`

Explanation:

`12=2+25t-5t^2`

`2+25t-5t^2=12`

`-5t^2+25t-10=0`

`(-25+√(25^2-4\left(-5\right)\left(-10\right)))/(2\left(-5\right))`

`(-25-√(25^2-4\left(-5\right)\left(-10\right)))/(2\left(-5\right))`

`t=(5-√(17))/(2),\:t=(5+√(17))/(2)`

`t=0.43845\dots ,\:t=4.56155\dots`