0=x^2+615x-90000

Solution for 0=x^2+615x-90000 equation:

0=x^2+615x-90000

We move all terms to the left:

0-(x^2+615x-90000)=0

We add all the numbers together, and all the variables

-(x^2+615x-90000)=0

We get rid of parentheses

-x^2-615x+90000=0

We add all the numbers together, and all the variables

-1x^2-615x+90000=0

a = -1; b = -615; c = +90000;
Δ = b2-4ac
Δ = -6152-4·(-1)·90000
Δ = 738225
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:

$\sqrt{\Delta}=\sqrt{738225}=\sqrt{225*3281}=\sqrt{225}*\sqrt{3281}=15\sqrt{3281}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-615)-15\sqrt{3281}}{2*-1}=\frac{615-15\sqrt{3281}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-615)+15\sqrt{3281}}{2*-1}=\frac{615+15\sqrt{3281}}{-2}
$