-30x+108=-2x^2

Solution for -30x+108=-2x^2 equation:

-30x+108=-2x^2

We move all terms to the left:

-30x+108-(-2x^2)=0

We get rid of parentheses

2x^2-30x+108=0

a = 2; b = -30; c = +108;
Δ = b2-4ac
Δ = -302-4·2·108
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-6}{2*2}=\frac{24}{4}
=6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+6}{2*2}=\frac{36}{4}
=9
$