Giải giùm minh câu 2 và 3 với ạ mình c mơn

`2,((sqrt{1})/7-(sqrt{16})/7+sqrt{7}):sqrt{7}`

`=(1/7-(sqrt{4^2})/7+sqrt{7}):sqrt{7}`

`=(1/7-4/7+sqrt{7}):sqrt{7}`

`=(-3/7+sqrt{7}):sqrt{7}`

`=-3/7 . 1/sqrt{7}+sqrt{7}:sqrt{7}`

`=-3/(7sqrt{7})+1`

`=-(3sqrt{7})/49+1`

`=(49-3sqrt{7})/49`

`3,(sqrt{10}-sqrt{15})/(sqrt{8}-sqrt{12})`

`=(sqrt{5}.sqrt{2}-sqrt{5}.sqrt{3})/(sqrt{4.2}-sqrt{4.3})`

`=(sqrt{5}(sqrt{2}-sqrt{3}))/(2sqrt{2}-2sqrt{3})`

`=(sqrt{5}(sqrt{2}-sqrt{3}))/(2(sqrt{2}-sqrt{3}))`

`=(sqrt{5})/2.`