(10+2x)(26+2x)=1380

Solution for (10+2x)(26+2x)=1380 equation:

(10+2x)(26+2x)=1380

We move all terms to the left:

(10+2x)(26+2x)-(1380)=0

We add all the numbers together, and all the variables

(2x+10)(2x+26)-1380=0

We multiply parentheses ..

(+4x^2+52x+20x+260)-1380=0

We get rid of parentheses

4x^2+52x+20x+260-1380=0

We add all the numbers together, and all the variables

4x^2+72x-1120=0

a = 4; b = 72; c = -1120;
Δ = b2-4ac
Δ = 722-4·4·(-1120)
Δ = 23104
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{23104}=152$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-152}{2*4}=\frac{-224}{8}
=-28
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+152}{2*4}=\frac{80}{8}
=10
$