# -the equation x^2 + y^2 -4x+2y=b how do you determine the y coordinate of the center of the circle. Also,

###### Question:

-the equation x^2 + y^2 -4x+2y=b how do you determine the y coordinate of the center of the circle. Also, if the radius of the circle is 7 units, what is the value of b in the equation?