X2+8x=240

Solution for X2+8x=240 equation:

X2+8X=240

We move all terms to the left:

X2+8X-(240)=0

We add all the numbers together, and all the variables

X^2+8X-240=0

a = 1; b = 8; c = -240;
Δ = b2-4ac
Δ = 82-4·1·(-240)
Δ = 1024
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1024}=32$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-32}{2*1}=\frac{-40}{2}
=-20
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+32}{2*1}=\frac{24}{2}
=12
$