15=8x^2-2x

Solution for 15=8x^2-2x equation:

15=8x^2-2x

We move all terms to the left:

15-(8x^2-2x)=0

We get rid of parentheses

-8x^2+2x+15=0

a = -8; b = 2; c = +15;
Δ = b2-4ac
Δ = 22-4·(-8)·15
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-22}{2*-8}=\frac{-24}{-16}
=1+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+22}{2*-8}=\frac{20}{-16}
=-1+1/4
$