(x+x)(x+10)=1500

Solution for (x+x)(x+10)=1500 equation:

(x+x)(x+10)=1500

We move all terms to the left:

(x+x)(x+10)-(1500)=0

We add all the numbers together, and all the variables

(+2x)(x+10)-1500=0

We multiply parentheses ..

(+2x^2+20x)-1500=0

We get rid of parentheses

2x^2+20x-1500=0

a = 2; b = 20; c = -1500;
Δ = b2-4ac
Δ = 202-4·2·(-1500)
Δ = 12400
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:

$\sqrt{\Delta}=\sqrt{12400}=\sqrt{400*31}=\sqrt{400}*\sqrt{31}=20\sqrt{31}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-20\sqrt{31}}{2*2}=\frac{-20-20\sqrt{31}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+20\sqrt{31}}{2*2}=\frac{-20+20\sqrt{31}}{4}
$