problem 1: re-arrange g(x) function below to completed square form

g(x)=-x^2+4x+1

I know the answer is 5-(x-2)^2

But how to get the answer? Mind to show steps?

problem 2: determine the turning point (x,y)

the answer is (2,5) but how to determine which term belongs to x or y ? does the term inside the brackets of square belong to x and the constant is y as a fixed rule?

thank you