-30x^2+1200x+4000=13000

Solution for -30x^2+1200x+4000=13000 equation:

-30x^2+1200x+4000=13000

We move all terms to the left:

-30x^2+1200x+4000-(13000)=0

We add all the numbers together, and all the variables

-30x^2+1200x-9000=0

a = -30; b = 1200; c = -9000;
Δ = b2-4ac
Δ = 12002-4·(-30)·(-9000)
Δ = 360000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{360000}=600$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1200)-600}{2*-30}=\frac{-1800}{-60}
=+30
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1200)+600}{2*-30}=\frac{-600}{-60}
=+10
$