The equation x + y2-4x+2y=b describes a circle.

Part A

Determine the y-coordinate of the center of the circle.

Enter your answer in the box.

-1

Explanation:

The given equation can be written as

-3x + y^2 + 2y + 1=b+1

-3x + (y+1) ^2=b+1

(-3x-b) + (y+1) ^2=1

This is to be compared with (x-a) ^2 + (y-b) ^2=c^2

where (a, b) is the center, and c is the radius of the circle.

Thus, we get y=-1, and this is our answer.