3n^2+6n=15

Solution for 3n^2+6n=15 equation:

3n^2+6n=15

We move all terms to the left:

3n^2+6n-(15)=0

a = 3; b = 6; c = -15;
Δ = b2-4ac
Δ = 62-4·3·(-15)
Δ = 216
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{216}=\sqrt{36*6}=\sqrt{36}*\sqrt{6}=6\sqrt{6}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-6\sqrt{6}}{2*3}=\frac{-6-6\sqrt{6}}{6}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+6\sqrt{6}}{2*3}=\frac{-6+6\sqrt{6}}{6}
$