.83x^2+15=8x

Solution for .83x^2+15=8x equation:

.83x^2+15=8x

We move all terms to the left:

.83x^2+15-(8x)=0

a = .83; b = -8; c = +15;
Δ = b2-4ac
Δ = -82-4·.83·15
Δ = 14.2
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{-(-8)-\sqrt{14.2}}{2*.83}=\frac{8-\sqrt{14.2}}{1.66}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+\sqrt{14.2}}{2*.83}=\frac{8+\sqrt{14.2}}{1.66}
$