x*(x-6)=315

Solution for x*(x-6)=315 equation:

x(x-6)=315

We move all terms to the left:

x(x-6)-(315)=0

We multiply parentheses

x^2-6x-315=0

a = 1; b = -6; c = -315;
Δ = b2-4ac
Δ = -62-4·1·(-315)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-36}{2*1}=\frac{-30}{2}
=-15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+36}{2*1}=\frac{42}{2}
=21
$