To find the radius and center of the circle:
[tex]x^2+y^2-4x=0[/tex]we need to complete the squares in the x variable:
[tex]\begin{gathered} x^2+y^2-4x=0 \\ (x^2-4x)+y^2=0 \\ (x^2-4x+(-2)^2)+y^2=(-2)^2 \\ (x-2)^2+y^2=4 \end{gathered}[/tex]Therefore the center is the point (2,0) and the radius is 2.
The graph of the circle is:
