64=y^2-4y+4

Solution for 64=y^2-4y+4 equation:

64=y^2-4y+4

We move all terms to the left:

64-(y^2-4y+4)=0

We get rid of parentheses

-y^2+4y-4+64=0

We add all the numbers together, and all the variables

-1y^2+4y+60=0

a = -1; b = 4; c = +60;
Δ = b2-4ac
Δ = 42-4·(-1)·60
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-16}{2*-1}=\frac{-20}{-2}
=+10
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+16}{2*-1}=\frac{12}{-2}
=-6
$