x^2+2x^2=5.3^2

Solution for x^2+2x^2=5.3^2 equation:

x^2+2x^2=5.3^2

We move all terms to the left:

x^2+2x^2-(5.3^2)=0

We add all the numbers together, and all the variables

3x^2-28.09=0

a = 3; b = 0; c = -28.09;
Δ = b2-4ac
Δ = 02-4·3·(-28.09)
Δ = 337.08
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{337.08}}{2*3}=\frac{0-\sqrt{337.08}}{6}
=-\frac{\sqrt{}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{337.08}}{2*3}=\frac{0+\sqrt{337.08}}{6}
=\frac{\sqrt{}}{6}
$