x^2+2x^2=12.6

Solution for x^2+2x^2=12.6 equation:

x^2+2x^2=12.6

We move all terms to the left:

x^2+2x^2-(12.6)=0

We add all the numbers together, and all the variables

3x^2-12.6=0

a = 3; b = 0; c = -12.6;
Δ = b2-4ac
Δ = 02-4·3·(-12.6)
Δ = 151.2
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{151.2}}{2*3}=\frac{0-\sqrt{151.2}}{6}
=-\frac{\sqrt{}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{151.2}}{2*3}=\frac{0+\sqrt{151.2}}{6}
=\frac{\sqrt{}}{6}
$