[tex]x^2+y^2\text{ = 7 (option C)}[/tex]
Explanation:
Standard equation of circle:
[tex](x-h)^2+(y-k)^2=r^2[/tex][tex]\begin{gathered} \text{If centered at the origin:} \\ (h,\text{ k) = (0, 0)} \\ h\text{ = 0, k = 0} \end{gathered}[/tex][tex]\begin{gathered} \text{The equation of circle becomes:} \\ (x-0)^2+(y-0)^2=r^2 \\ x^2+y^2=r^2 \end{gathered}[/tex]
comparing the above equation with the options given:
[tex]\begin{gathered} x^2+y^2=7\text{ has the form} \\ x^2+y^2=r^2,wherer^2\text{= }7 \end{gathered}[/tex][tex]x^2+y^2\text{ = 7 (option C)}[/tex]
