we have to step by step make y alone on it's side.
First, we subtract 1 from both sides:
x-1=(y-1)^2
Let's already invert the Left hand side and the right hand side:
(y-1)^2=x-1
now we need to get a square root of both sides:
\((y-1)=+/- \sqrt{x-1}\)
and add 1:
\(y=+/- \sqrt{x-1}\)+1