15=6x^2

Solution for 15=6x^2 equation:

15=6x^2

We move all terms to the left:

15-(6x^2)=0

a = -6; b = 0; c = +15;
Δ = b2-4ac
Δ = 02-4·(-6)·15
Δ = 360
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:

$\sqrt{\Delta}=\sqrt{360}=\sqrt{36*10}=\sqrt{36}*\sqrt{10}=6\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{10}}{2*-6}=\frac{0-6\sqrt{10}}{-12}
=-\frac{6\sqrt{10}}{-12}
=-\frac{\sqrt{10}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{10}}{2*-6}=\frac{0+6\sqrt{10}}{-12}
=\frac{6\sqrt{10}}{-12}
=\frac{\sqrt{10}}{-2}
$