True or False:

•Every equation of the form
X^2+y^2+ax+by+c=c

•The radius of the circle
x^2+y^2=9 is 3

•The center of the circle
(X+3)^2+(y-2)^2=13 is (3,-2)

3 answers

I do not know what the first one is supposed to be, either a typo or totally false
The second is true
the third has the signs backwards, should be (-3 ,2)
Looks like the first one is intended to be the equation of a circle.

(x^2 + ax) + (y^2 + by) = 0

Unfortunately, if a or b is not zero, there is no real graph.

If a=b=0, then the graph is just the point (0,0).

If there was a typo, giving a "d" on the right-hand side, then given suitable a,b,c,d there will be a circle that satisfies the equation.
Oh yes the first one was a typo it was supposed to be X^2+y^2+ax+by+c=0