X^2+8x-128=225

Solution for X^2+8x-128=225 equation:

X^2+8X-128=225

We move all terms to the left:

X^2+8X-128-(225)=0

We add all the numbers together, and all the variables

X^2+8X-353=0

a = 1; b = 8; c = -353;
Δ = b2-4ac
Δ = 82-4·1·(-353)
Δ = 1476
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:

$\sqrt{\Delta}=\sqrt{1476}=\sqrt{36*41}=\sqrt{36}*\sqrt{41}=6\sqrt{41}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-6\sqrt{41}}{2*1}=\frac{-8-6\sqrt{41}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+6\sqrt{41}}{2*1}=\frac{-8+6\sqrt{41}}{2}
$