\(\sqrt{112} = \sqrt{16} ⋅ \sqrt{7} = 4 \sqrt{7} \text{.}\)

\(-2 \sqrt{48} = -2 ⋅ \sqrt{16} ⋅ \sqrt{3} = -2 ⋅ 4 ⋅ \sqrt{3} = -8 \sqrt{3} \text{.}\)

\(\sqrt{\frac{25}{81}} = {\sqrt{25} \over \sqrt{81}} = \frac{5}{9} \text{.}\)

\({42 \sqrt{144} \over 7 \sqrt{6}} = {42 \over 7} ⋅ {\sqrt{144} \over \sqrt{6}} = 6 \sqrt{24} = 6 ⋅ \sqrt{4} ⋅ \sqrt{6} = 6 ⋅ 2 ⋅ \sqrt{6} = 12 \sqrt{6}\)