Math Help: Solve x = y^2 - 8*y + 16 for y ?

Question

My mind is completely blank...this is a first step to a more complicated problem. Can you get me started on it? I am drawing a blank. Solve x = y^2 - 8*y + 16 for y to obtain two functions that represent the upper and lower branches of the parabola.
Thanks!

Answer 1

Look this is just x=(y-4)^2. So x has to be >=0 and
y-4 is + or - sqrt{x}

Answer 2

y=x+4