13x^2=90

Solution for 13x^2=90 equation:

13x^2=90

We move all terms to the left:

13x^2-(90)=0

a = 13; b = 0; c = -90;
Δ = b2-4ac
Δ = 02-4·13·(-90)
Δ = 4680
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:

$\sqrt{\Delta}=\sqrt{4680}=\sqrt{36*130}=\sqrt{36}*\sqrt{130}=6\sqrt{130}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{130}}{2*13}=\frac{0-6\sqrt{130}}{26}
=-\frac{6\sqrt{130}}{26}
=-\frac{3\sqrt{130}}{13}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{130}}{2*13}=\frac{0+6\sqrt{130}}{26}
=\frac{6\sqrt{130}}{26}
=\frac{3\sqrt{130}}{13}
$