Question

PLEASE HELP ME ON THIS MATH QUESTION :)

Answer 1

Equation of a circle in standard form with center (h,k) and radius r is given by :

`(x-h)^(2) +(y-k)^(2) =r^(2)`

In the given question the center of circle is lying on y axis so h=0 .Radius r=3 Substituting these values in the equation of circle we have:

`(x-0)^2+(y-k)^2=3^2`

Expanding we have :

`x^2+y^2-2yk+h^2=9`

Subtracting 9 both sides

`x^2+y^2-2yk+h^2-9=0`

Comparing this with the equation of circle in general form

A=1,B=1,C=0

If D=-8 then E=7

So option C is the right answer