x^2-9x=30

Solution for x^2-9x=30 equation:

x^2-9x=30

We move all terms to the left:

x^2-9x-(30)=0

a = 1; b = -9; c = -30;
Δ = b2-4ac
Δ = -92-4·1·(-30)
Δ = 201
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-\sqrt{201}}{2*1}=\frac{9-\sqrt{201}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{201}}{2*1}=\frac{9+\sqrt{201}}{2}
$