-5x(2x-5)=0

Solution for -5x(2x-5)=0 equation:

-5x(2x-5)=0

We multiply parentheses

-10x^2+25x=0

a = -10; b = 25; c = 0;
Δ = b2-4ac
Δ = 252-4·(-10)·0
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-25}{2*-10}=\frac{-50}{-20}
=2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+25}{2*-10}=\frac{0}{-20}
=0
$