(28-2x)(22-2x)=722

Solution for (28-2x)(22-2x)=722 equation:

(28-2x)(22-2x)=722

We move all terms to the left:

(28-2x)(22-2x)-(722)=0

We add all the numbers together, and all the variables

(-2x+28)(-2x+22)-722=0

We multiply parentheses ..

(+4x^2-44x-56x+616)-722=0

We get rid of parentheses

4x^2-44x-56x+616-722=0

We add all the numbers together, and all the variables

4x^2-100x-106=0

a = 4; b = -100; c = -106;
Δ = b2-4ac
Δ = -1002-4·4·(-106)
Δ = 11696
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:

$\sqrt{\Delta}=\sqrt{11696}=\sqrt{16*731}=\sqrt{16}*\sqrt{731}=4\sqrt{731}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-4\sqrt{731}}{2*4}=\frac{100-4\sqrt{731}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+4\sqrt{731}}{2*4}=\frac{100+4\sqrt{731}}{8}
$