-18x=2x^2+28

Solution for -18x=2x^2+28 equation:

-18x=2x^2+28

We move all terms to the left:

-18x-(2x^2+28)=0

We get rid of parentheses

-2x^2-18x-28=0

a = -2; b = -18; c = -28;
Δ = b2-4ac
Δ = -182-4·(-2)·(-28)
Δ = 100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{100}=10$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-10}{2*-2}=\frac{8}{-4}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+10}{2*-2}=\frac{28}{-4}
=-7
$