12x^2-18=-15x

Solution for 12x^2-18=-15x equation:

12x^2-18=-15x

We move all terms to the left:

12x^2-18-(-15x)=0

We get rid of parentheses

12x^2+15x-18=0

a = 12; b = 15; c = -18;
Δ = b2-4ac
Δ = 152-4·12·(-18)
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-33}{2*12}=\frac{-48}{24}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+33}{2*12}=\frac{18}{24}
=3/4
$