Posted by Jamie on .
A water balloon is catapulted into the air so that its height, h, in metres after t seconds is h=4.9t^2+25t+1.9.
when is the ball 13 m high?

Math Grade 11 U 
bobpursley,
put h=13, put it in standard form
ax^2+bx+c=0
and use the quadratic equation to solve for x.