Đáp án + Giải thích các bước giải:
Câu 2:
`b.`
`sqrt(12+2sqrt35)-sqrt(8-2sqrt15)`
`=sqrt(7+2sqrt35+5)-sqrt(5-2sqrt15+3)`
`=sqrt((sqrt7)^2+2sqrt7.sqrt5+(sqrt5)^2)-sqrt((sqrt5)^2-2sqrt5.sqrt3+(sqrt3)^2)`
`=sqrt((sqrt7+sqrt5)^2)-sqrt((sqrt5-sqrt3)^2)`
`=|sqrt7+sqrt5|-|sqrt5-sqrt3|`
`=sqrt7+sqrt5-(sqrt5-sqrt3)`
`=sqrt7+sqrt5-sqrt5+sqrt3`
`=sqrt7+sqrt3`