Đáp án + Giải thích các bước giải:
Câu `35` :
`a)` `A=3sqrt27-2sqrt12+4sqrt48`
`=3sqrt(3^2*3)-2sqrt(2^2*3)+4sqrt(2^2*2^2*3)`
`=3*3sqrt3-2*2sqrt3+4*2*2sqrt3`
`=9sqrt3-4sqrt3+16sqrt3`
`=(9-4+16)sqrt3=21sqrt3`
`b)` `B=sqrt(7-4sqrt3)+1/(2-sqrt3)`
`=sqrt(4-4sqrt3+3)+(2+sqrt3)/[(2-sqrt3)(2+sqrt3)]`
`=sqrt(4-2*2sqrt3+3)+(2+sqrt3)/(4-3)`
`=sqrt(2^2-2*2*sqrt3+(sqrt3)^2)+(2+sqrt3)`
`=sqrt[(2-sqrt3)^2]+(2+sqrt3)`
`=|2-sqrt3|+2+sqrt3=2-sqrt3+2+sqrt3=4`
