x2-5x+9+2-8x+x2=18

Solution for x2-5x+9+2-8x+x2=18 equation:

x2-5x+9+2-8x+x2=18

We move all terms to the left:

x2-5x+9+2-8x+x2-(18)=0

We add all the numbers together, and all the variables

2x^2-13x-7=0

a = 2; b = -13; c = -7;
Δ = b2-4ac
Δ = -132-4·2·(-7)
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-15}{2*2}=\frac{-2}{4}
=-1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+15}{2*2}=\frac{28}{4}
=7
$