x^2-x-13=2x+5

Solution for x^2-x-13=2x+5 equation:

x^2-x-13=2x+5

We move all terms to the left:

x^2-x-13-(2x+5)=0

We add all the numbers together, and all the variables

x^2-1x-(2x+5)-13=0

We get rid of parentheses

x^2-1x-2x-5-13=0

We add all the numbers together, and all the variables

x^2-3x-18=0

a = 1; b = -3; c = -18;
Δ = b2-4ac
Δ = -32-4·1·(-18)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-9}{2*1}=\frac{-6}{2}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+9}{2*1}=\frac{12}{2}
=6
$