Using the quadratic formula b²-4b+4=0

If you need to use  the Quadratic Formula, it could also look something like this:
(1)b² + (-4)b + (4) = 0
These represent a, b, and c in their respective order.
The equation itself is:
(-b (+/-) √(b² - 4ac))/2a
So, plug 'em in:
(4 (+/-) √(-4² - 4·1·4))/2·1
And then solve:
(4 (+/-) √(16 - 16))/2
(4 (+/-) 0)/2
4/2
2