What is the radius of the circle given by the equation below?

Question

anonymous · Answer

attachment

anonymous · Answer

haha these are so easy

anonymous · Answer

D

anonymous · Answer

The best way to do this one is to write everything in terms of y and then plug it into a graphing calculator. But the other by hand method would be factoring the formula given. Hope I helped.

anonymous · Answer

not really
you have to  first write at 
$$x^2-6x+y^2-18y=-26$$ and then complete the square twice

anonymous · Answer

forget the graphing calculator
or any calculator
do you know how to complete the square ?

anonymous · Answer

@satellite73 I think using b/2 right?

anonymous · Answer

yeah you have to do it twice 
$$(x-3)^2+(y-9)^2=-26+9+81$$

anonymous · Answer

or 
$$(x-3)^2+(y-9)^2=64$$ making the center $(3,9)$ and the radius $\sqrt{64}=8$