812=(16+2x)(28+2x)

Solution for 812=(16+2x)(28+2x) equation:

812=(16+2x)(28+2x)

We move all terms to the left:

812-((16+2x)(28+2x))=0

We add all the numbers together, and all the variables

-((2x+16)(2x+28))+812=0

We multiply parentheses ..

-((+4x^2+56x+32x+448))+812=0


We calculate terms in parentheses: -((+4x^2+56x+32x+448)), so:

(+4x^2+56x+32x+448)

We get rid of parentheses

4x^2+56x+32x+448

We add all the numbers together, and all the variables

4x^2+88x+448

Back to the equation:

-(4x^2+88x+448)


We get rid of parentheses

-4x^2-88x-448+812=0

We add all the numbers together, and all the variables

-4x^2-88x+364=0

a = -4; b = -88; c = +364;
Δ = b2-4ac
Δ = -882-4·(-4)·364
Δ = 13568
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:

$\sqrt{\Delta}=\sqrt{13568}=\sqrt{256*53}=\sqrt{256}*\sqrt{53}=16\sqrt{53}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-88)-16\sqrt{53}}{2*-4}=\frac{88-16\sqrt{53}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-88)+16\sqrt{53}}{2*-4}=\frac{88+16\sqrt{53}}{-8}
$