F2數-根式!我唔知點做呢D就唔知點做日後的功課!

1. √3+ 4√3
=5√3
2. 7√2- 2√2
=5√2
3.√18 - √72
=√18 - √4*√18
=√18(1-√4)
4.√28 + √112
=√28 + √4*√28
=√28(1+√4)
5.√2 x √12
=√2 x√2*√6
=4√6
6.√6 x √30
=√6 x √6*√5
=6√5
7.√63 除 √21
=√21*√3 / √21
=√3
8.√144 除 √6
=√6*√24 / √6
=√24
9.√128 除 √10
=√2*√64 / √2* √5
=√2(√64 / √5)