Question 267528
with centre C(2 ; 3) and which is tangent to the x-axis.

since the circle is tangent to the x-axis 
the radius will be 3 units (y coordinate of the centre)

now the equation of the circle with center (x1,y1) and radius r is

(x-x1)^2 + (y-y1)^2 = r^2

so the eq. is {{{(x-2)^2+(y-3)^2=9}}}

if we expand we get 

            {{{x^2+y^2-4x-6y+4=0}}}