6.21=c^2

Solution for 6.21=c^2 equation:

6.21=c^2

We move all terms to the left:

6.21-(c^2)=0

We add all the numbers together, and all the variables

-1c^2+6.21=0

a = -1; b = 0; c = +6.21;
Δ = b2-4ac
Δ = 02-4·(-1)·6.21
Δ = 24.84
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{24.84}}{2*-1}=\frac{0-\sqrt{24.84}}{-2}
=-\frac{\sqrt{}}{-2}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{24.84}}{2*-1}=\frac{0+\sqrt{24.84}}{-2}
=\frac{\sqrt{}}{-2}
$