PreCalc
posted by nelly .
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+(y2)^2=13 is (3,2)

PreCalc 
Damon
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) 
PreCalc 
Steve
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 righthand side, then given suitable a,b,c,d there will be a circle that satisfies the equation. 
PreCalc 
nelly
Oh yes the first one was a typo it was supposed to be X^2+y^2+ax+by+c=0
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