Question 27151
When your diver hits the pool will be when y (elevation) equals 0. Of course since this is a quadratic equation it will have two answers, but one of them will be negative and make no sense.

You're right, it doesn't factor. So you can use the quadratic formula to solve it:

{{{(-b +- sqrt( b^2-4*a*c ))/(2*a)}}}
{{{(-15+-sqrt(15^2-4(-2)(6)))/(2*(-2))}}}
{{{(-15+-sqrt(273))/(-4)}}}
{{{(15+-16.523)/4}}}
{{{31.523/4}}}{{{-1.523/4}}}
{{{7.88}}}{{{-0.381}}}
So the only possible answer is 7.88 (AKA {{{(15+sqrt(273))/4}}})

Graphically the dive looks like:
{{{graph( 230, 200, -1,10, -3,35, (-2x^2+15x+6))}}}