(X+2)(y-4)=240

Solution for (X+2)(y-4)=240 equation:

(X+2)(X-4)=240

We move all terms to the left:

(X+2)(X-4)-(240)=0

We multiply parentheses ..

(+X^2-4X+2X-8)-240=0

We get rid of parentheses

X^2-4X+2X-8-240=0

We add all the numbers together, and all the variables

X^2-2X-248=0

a = 1; b = -2; c = -248;
Δ = b2-4ac
Δ = -22-4·1·(-248)
Δ = 996
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{996}=\sqrt{4*249}=\sqrt{4}*\sqrt{249}=2\sqrt{249}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2\sqrt{249}}{2*1}=\frac{2-2\sqrt{249}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2\sqrt{249}}{2*1}=\frac{2+2\sqrt{249}}{2}
$