Hướng dẫn trả lời:
a) `3sqrt5 = sqrt{3^2 .5} = sqrt9.5 = sqrt45.`
b) `10sqrt{0,21} = sqrt{10^2 .0,21} = sqrt{100.0,21} = sqrt{21}.`
c) `3/2.sqrt{5/3} = sqrt{(3/2)^2. 5/3} = sqrt{9/4. 5/3} = sqrt{15/4}.`
d) `-4sqrt{3} = - sqrt{4^2 .3} = sqrt{16.3} = sqrt{48}.`
e) `-0,3sqrt{10} = - sqrt{0,3^2. 10} = - sqrt{0,09.10} = - sqrt{0,9}.`
f) `-3/5sqrt{50} = - sqrt{(3/5)^2 .50} = - sqrt{9/25 .50} = - sqrt{9.2} = - sqrt{18}.`