Answer
$x^{2}+y^{2}=49$
Work Step by Step
We know that the standard form of the equation of a circle with center $(h,k)$ and radius $r$ is $(x-h)^{2}+(y-k)^{2}=r^{2}$.
Therefore, we can plug in the given values for $h$, $k$, and $r$ and simplify.
$(x-0)^{2}+(y-0)^{2}=(7)^{2}$
$x^{2}+y^{2}=49$