3x^2-1=x^2+9

Solution for 3x^2-1=x^2+9 equation:

3x^2-1=x^2+9

We move all terms to the left:

3x^2-1-(x^2+9)=0

We get rid of parentheses

3x^2-x^2-9-1=0

We add all the numbers together, and all the variables

2x^2-10=0

a = 2; b = 0; c = -10;
Δ = b2-4ac
Δ = 02-4·2·(-10)
Δ = 80
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:

$\sqrt{\Delta}=\sqrt{80}=\sqrt{16*5}=\sqrt{16}*\sqrt{5}=4\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{5}}{2*2}=\frac{0-4\sqrt{5}}{4}
=-\frac{4\sqrt{5}}{4}
=-\sqrt{5}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{5}}{2*2}=\frac{0+4\sqrt{5}}{4}
=\frac{4\sqrt{5}}{4}
=\sqrt{5}
$