-8=18x-5x2

Solution for -8=18x-5x2 equation:

-8=18x-5x^2

We move all terms to the left:

-8-(18x-5x^2)=0

We get rid of parentheses

5x^2-18x-8=0

a = 5; b = -18; c = -8;
Δ = b2-4ac
Δ = -182-4·5·(-8)
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{-(-18)-22}{2*5}=\frac{-4}{10}
=-2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+22}{2*5}=\frac{40}{10}
=4
$