-x2+2980x=30

Solution for -x2+2980x=30 equation:

-x2+2980x=30

We move all terms to the left:

-x2+2980x-(30)=0

We add all the numbers together, and all the variables

-1x^2+2980x-30=0

a = -1; b = 2980; c = -30;
Δ = b2-4ac
Δ = 29802-4·(-1)·(-30)
Δ = 8880280
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:

$\sqrt{\Delta}=\sqrt{8880280}=\sqrt{4*2220070}=\sqrt{4}*\sqrt{2220070}=2\sqrt{2220070}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2980)-2\sqrt{2220070}}{2*-1}=\frac{-2980-2\sqrt{2220070}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2980)+2\sqrt{2220070}}{2*-1}=\frac{-2980+2\sqrt{2220070}}{-2}
$