What is the answer nto this qustion

How do i do this? i don’t understand

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).