y2 - 5y + 2x - x2 - 120 is not a circle. It is a hyperbola rotated through 90 degrees.
x2 + y2 - 5y + 4 = 0 x2 + y2 - 5y = - 4 x2 + y2 - 5y + 25/4 = - 4 + 25/4 = 9/4 x2 + (y - 5/2)2 = (3/2)2 Centre = (0, 5/2) and radius = 3/2
This not a circle, both the squared terms must have the same coefficients if it might be a circle. Different signs indicate a hyperbola.
x2 + y2 = 2r2
Type your answer here. Find the radius for a circle with the equation x2 plus y2 equals 9? ..
no
4
9
7
8
Radius = 1111
The ' 1 ' in that equation is the radius.