3x^2-9=-3x^2+15

Solution for 3x^2-9=-3x^2+15 equation:

3x^2-9=-3x^2+15

We move all terms to the left:

3x^2-9-(-3x^2+15)=0

We get rid of parentheses

3x^2+3x^2-15-9=0

We add all the numbers together, and all the variables

6x^2-24=0

a = 6; b = 0; c = -24;
Δ = b2-4ac
Δ = 02-4·6·(-24)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-24}{2*6}=\frac{-24}{12}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+24}{2*6}=\frac{24}{12}
=2
$