X^2+4x-18=8

Solution for X^2+4x-18=8 equation:

X^2+4X-18=8

We move all terms to the left:

X^2+4X-18-(8)=0

We add all the numbers together, and all the variables

X^2+4X-26=0

a = 1; b = 4; c = -26;
Δ = b2-4ac
Δ = 42-4·1·(-26)
Δ = 120
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:

$\sqrt{\Delta}=\sqrt{120}=\sqrt{4*30}=\sqrt{4}*\sqrt{30}=2\sqrt{30}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{30}}{2*1}=\frac{-4-2\sqrt{30}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{30}}{2*1}=\frac{-4+2\sqrt{30}}{2}
$