x(x-28)=0

Solution for x(x-28)=0 equation:

x(x-28)=0

We multiply parentheses

x^2-28x=0

a = 1; b = -28; c = 0;
Δ = b2-4ac
Δ = -282-4·1·0
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-28}{2*1}=\frac{0}{2}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+28}{2*1}=\frac{56}{2}
=28
$