4c^2-64=4c

Solution for 4c^2-64=4c equation:

4c^2-64=4c

We move all terms to the left:

4c^2-64-(4c)=0

a = 4; b = -4; c = -64;
Δ = b2-4ac
Δ = -42-4·4·(-64)
Δ = 1040
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1040}=\sqrt{16*65}=\sqrt{16}*\sqrt{65}=4\sqrt{65}$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-4\sqrt{65}}{2*4}=\frac{4-4\sqrt{65}}{8}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+4\sqrt{65}}{2*4}=\frac{4+4\sqrt{65}}{8}
$