Rewrite the square root of the division $\sqrt{\frac{789}{98}}$ as the division of square roots $\frac{\sqrt{789}}{\sqrt{98}}$.
$$\frac{\sqrt{789}}{\sqrt{98}}$$
Factor $98=7^{2}\times 2$. Rewrite the square root of the product $\sqrt{7^{2}\times 2}$ as the product of square roots $\sqrt{7^{2}}\sqrt{2}$. Take the square root of $7^{2}$.
$$\frac{\sqrt{789}}{7\sqrt{2}}$$
Rationalize the denominator of $\frac{\sqrt{789}}{7\sqrt{2}}$ by multiplying numerator and denominator by $\sqrt{2}$.
