2n^2-n^2-5n=12

Solution for 2n^2-n^2-5n=12 equation:

2n^2-n^2-5n=12

We move all terms to the left:

2n^2-n^2-5n-(12)=0

We add all the numbers together, and all the variables

n^2-5n-12=0

a = 1; b = -5; c = -12;
Δ = b2-4ac
Δ = -52-4·1·(-12)
Δ = 73
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{73}}{2*1}=\frac{5-\sqrt{73}}{2}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{73}}{2*1}=\frac{5+\sqrt{73}}{2}
$