x+(x+13)+(x2)=125

Solution for x+(x+13)+(x2)=125 equation:

x+(x+13)+(x2)=125

We move all terms to the left:

x+(x+13)+(x2)-(125)=0

We add all the numbers together, and all the variables

x^2+x+(x+13)-125=0

We get rid of parentheses

x^2+x+x+13-125=0

We add all the numbers together, and all the variables

x^2+2x-112=0

a = 1; b = 2; c = -112;
Δ = b2-4ac
Δ = 22-4·1·(-112)
Δ = 452
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:

$\sqrt{\Delta}=\sqrt{452}=\sqrt{4*113}=\sqrt{4}*\sqrt{113}=2\sqrt{113}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2\sqrt{113}}{2*1}=\frac{-2-2\sqrt{113}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2\sqrt{113}}{2*1}=\frac{-2+2\sqrt{113}}{2}
$