x^2-9x=56

Solution for x^2-9x=56 equation:

x^2-9x=56

We move all terms to the left:

x^2-9x-(56)=0

a = 1; b = -9; c = -56;
Δ = b2-4ac
Δ = -92-4·1·(-56)
Δ = 305
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{305}}{2*1}=\frac{9-\sqrt{305}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{305}}{2*1}=\frac{9+\sqrt{305}}{2}
$