(20+2x)(30+2x)=1656

Solution for (20+2x)(30+2x)=1656 equation:

(20+2x)(30+2x)=1656

We move all terms to the left:

(20+2x)(30+2x)-(1656)=0

We add all the numbers together, and all the variables

(2x+20)(2x+30)-1656=0

We multiply parentheses ..

(+4x^2+60x+40x+600)-1656=0

We get rid of parentheses

4x^2+60x+40x+600-1656=0

We add all the numbers together, and all the variables

4x^2+100x-1056=0

a = 4; b = 100; c = -1056;
Δ = b2-4ac
Δ = 1002-4·4·(-1056)
Δ = 26896
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{26896}=164$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-164}{2*4}=\frac{-264}{8}
=-33
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+164}{2*4}=\frac{64}{8}
=8
$