0=-2x^2+99x+720

Solution for 0=-2x^2+99x+720 equation:

0=-2x^2+99x+720

We move all terms to the left:

0-(-2x^2+99x+720)=0

We add all the numbers together, and all the variables

-(-2x^2+99x+720)=0

We get rid of parentheses

2x^2-99x-720=0

a = 2; b = -99; c = -720;
Δ = b2-4ac
Δ = -992-4·2·(-720)
Δ = 15561
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{15561}=\sqrt{9*1729}=\sqrt{9}*\sqrt{1729}=3\sqrt{1729}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-99)-3\sqrt{1729}}{2*2}=\frac{99-3\sqrt{1729}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-99)+3\sqrt{1729}}{2*2}=\frac{99+3\sqrt{1729}}{4}
$