(26+2x)(36+2x)=1200

Solution for (26+2x)(36+2x)=1200 equation:

(26+2x)(36+2x)=1200

We move all terms to the left:

(26+2x)(36+2x)-(1200)=0

We add all the numbers together, and all the variables

(2x+26)(2x+36)-1200=0

We multiply parentheses ..

(+4x^2+72x+52x+936)-1200=0

We get rid of parentheses

4x^2+72x+52x+936-1200=0

We add all the numbers together, and all the variables

4x^2+124x-264=0

a = 4; b = 124; c = -264;
Δ = b2-4ac
Δ = 1242-4·4·(-264)
Δ = 19600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{19600}=140$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(124)-140}{2*4}=\frac{-264}{8}
=-33
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(124)+140}{2*4}=\frac{16}{8}
=2
$