X(x-20)=96

Solution for X(x-20)=96 equation:

X(X-20)=96

We move all terms to the left:

X(X-20)-(96)=0

We multiply parentheses

X^2-20X-96=0

a = 1; b = -20; c = -96;
Δ = b2-4ac
Δ = -202-4·1·(-96)
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{-(-20)-28}{2*1}=\frac{-8}{2}
=-4
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+28}{2*1}=\frac{48}{2}
=24
$