-3x2+18=6x2

Solution for -3x2+18=6x2 equation:

-3x^2+18=6x^2

We move all terms to the left:

-3x^2+18-(6x^2)=0

We add all the numbers together, and all the variables

-9x^2+18=0

a = -9; b = 0; c = +18;
Δ = b2-4ac
Δ = 02-4·(-9)·18
Δ = 648
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{648}=\sqrt{324*2}=\sqrt{324}*\sqrt{2}=18\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-18\sqrt{2}}{2*-9}=\frac{0-18\sqrt{2}}{-18}
=-\frac{18\sqrt{2}}{-18}
=-\frac{\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+18\sqrt{2}}{2*-9}=\frac{0+18\sqrt{2}}{-18}
=\frac{18\sqrt{2}}{-18}
=\frac{\sqrt{2}}{-1}
$