#### Answer

$\color{blue}{(x-\sqrt5)^2+(y+\sqrt7)^2=3}$

#### Work Step by Step

RECALL:
The center-radius form of a circle whose center is at $(h, k)$ and whose radius is $r$ units is:
$(x-h)^2+(y-k)^2=r^2$
The given circle has its center at $(\sqrt5, -\sqrt7)$ and has a radius of 15 units.
Thus, its equation in center-radius form is :
$(x-\sqrt5)^2+(y-(-\sqrt7))^2=(\sqrt3)^2
\\\color{blue}{(x-\sqrt5)^2+(y+\sqrt7)^2=3}$