21k^2=63

Solution for 21k^2=63 equation:

21k^2=63

We move all terms to the left:

21k^2-(63)=0

a = 21; b = 0; c = -63;
Δ = b2-4ac
Δ = 02-4·21·(-63)
Δ = 5292
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{5292}=\sqrt{1764*3}=\sqrt{1764}*\sqrt{3}=42\sqrt{3}$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-42\sqrt{3}}{2*21}=\frac{0-42\sqrt{3}}{42}
=-\frac{42\sqrt{3}}{42}
=-\sqrt{3}
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+42\sqrt{3}}{2*21}=\frac{0+42\sqrt{3}}{42}
=\frac{42\sqrt{3}}{42}
=\sqrt{3}
$