3x^2-5=243

Solution for 3x^2-5=243 equation:

3x^2-5=243

We move all terms to the left:

3x^2-5-(243)=0

We add all the numbers together, and all the variables

3x^2-248=0

a = 3; b = 0; c = -248;
Δ = b2-4ac
Δ = 02-4·3·(-248)
Δ = 2976
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:

$\sqrt{\Delta}=\sqrt{2976}=\sqrt{16*186}=\sqrt{16}*\sqrt{186}=4\sqrt{186}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{186}}{2*3}=\frac{0-4\sqrt{186}}{6}
=-\frac{4\sqrt{186}}{6}
=-\frac{2\sqrt{186}}{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{186}}{2*3}=\frac{0+4\sqrt{186}}{6}
=\frac{4\sqrt{186}}{6}
=\frac{2\sqrt{186}}{3}
$