(22-2x)(28-2x)=391

Solution for (22-2x)(28-2x)=391 equation:

(22-2x)(28-2x)=391

We move all terms to the left:

(22-2x)(28-2x)-(391)=0

We add all the numbers together, and all the variables

(-2x+22)(-2x+28)-391=0

We multiply parentheses ..

(+4x^2-56x-44x+616)-391=0

We get rid of parentheses

4x^2-56x-44x+616-391=0

We add all the numbers together, and all the variables

4x^2-100x+225=0

a = 4; b = -100; c = +225;
Δ = b2-4ac
Δ = -1002-4·4·225
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-80}{2*4}=\frac{20}{8}
=2+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+80}{2*4}=\frac{180}{8}
=22+1/2
$