15x(x-5)=0

Solution for 15x(x-5)=0 equation:

15x(x-5)=0

We multiply parentheses

15x^2-75x=0

a = 15; b = -75; c = 0;
Δ = b2-4ac
Δ = -752-4·15·0
Δ = 5625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5625}=75$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-75)-75}{2*15}=\frac{0}{30}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-75)+75}{2*15}=\frac{150}{30}
=5
$