9t^2+30t-72=0

Solution for 9t^2+30t-72=0 equation:

9t^2+30t-72=0

a = 9; b = 30; c = -72;
Δ = b2-4ac
Δ = 302-4·9·(-72)
Δ = 3492
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3492}=\sqrt{36*97}=\sqrt{36}*\sqrt{97}=6\sqrt{97}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-6\sqrt{97}}{2*9}=\frac{-30-6\sqrt{97}}{18}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+6\sqrt{97}}{2*9}=\frac{-30+6\sqrt{97}}{18}
$