X2-15x-16=-8

Solution for X2-15x-16=-8 equation:

X2-15X-16=-8

We move all terms to the left:

X2-15X-16-(-8)=0

We add all the numbers together, and all the variables

X^2-15X-8=0

a = 1; b = -15; c = -8;
Δ = b2-4ac
Δ = -152-4·1·(-8)
Δ = 257
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-\sqrt{257}}{2*1}=\frac{15-\sqrt{257}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{257}}{2*1}=\frac{15+\sqrt{257}}{2}
$