(5x-15)x=540

Solution for (5x-15)x=540 equation:

(5x-15)x=540

We move all terms to the left:

(5x-15)x-(540)=0

We multiply parentheses

5x^2-15x-540=0

a = 5; b = -15; c = -540;
Δ = b2-4ac
Δ = -152-4·5·(-540)
Δ = 11025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{11025}=105$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-105}{2*5}=\frac{-90}{10}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+105}{2*5}=\frac{120}{10}
=12
$