122. Get rid of the irrationality in the denominator of the fraction

$$
\frac{2+\sqrt{3}}{\sqrt{6}-\sqrt{3}+\sqrt{2}-1} .
$$
Solution. Multiplying the numerator and the denominator of the fraction by 2, we will have:

$$
\frac{2+\sqrt{3}}{\sqrt{6}-\sqrt{3}+\sqrt{2}-1}=\frac{(\sqrt{3}+1)^{2}}{2(\sqrt{3}+1)(\sqrt{2}-1)}=\frac{1}{2}(\sqrt{3}+1)(\sqrt{2}+1)
$$