Question 136159
Given: {{{h = -12t2 + 14t + 40  }}}
You are asked to find the time(s) when the ball is 40 feet above the ground.

{{{h = -12t2 + 14t + 40 }}}
{{{40= -12t2 + 14t + 40  }}}
{{{ 0 = -12t^2 + 14t}}}
{{{0 = -2t(6t - 7) }}}
the value is 0, if either or both terms on the right are 0.

So, 0 = -2t --> t = 0
0 = (6t-7) --> t = 7/6  

The ball is at 40 feet when you throw it, and again 7/6 seconds later

Check your answer

{{{h = -12(7/6)^2 + 14(7/6) + 40 }}}
{{{h = -16.333 + 16.333 + 40 }}}
{{{h = 40 }}} check