26=13v^2

Solution for 26=13v^2 equation:

26=13v^2

We move all terms to the left:

26-(13v^2)=0

a = -13; b = 0; c = +26;
Δ = b2-4ac
Δ = 02-4·(-13)·26
Δ = 1352
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1352}=\sqrt{676*2}=\sqrt{676}*\sqrt{2}=26\sqrt{2}$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-26\sqrt{2}}{2*-13}=\frac{0-26\sqrt{2}}{-26}
=-\frac{26\sqrt{2}}{-26}
=-\frac{\sqrt{2}}{-1}
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+26\sqrt{2}}{2*-13}=\frac{0+26\sqrt{2}}{-26}
=\frac{26\sqrt{2}}{-26}
=\frac{\sqrt{2}}{-1}
$