Đáp án+Giải thích các bước giải:
`a)sqrt8/(sqrt5-sqrt3)`
`=(sqrt8(sqrt5+sqrt3))/(5-3)`
`=(2sqrt2(sqrt5+sqrt3))/2`
`=sqrt2(sqrt5+sqrt3)`
`=sqrt10+sqrt6`
`b)sqrt{(2-sqrt3)/(2+sqrt3)}`
`=sqrt{(2-sqrt3)^2/(4-3)}`
`=|2-sqrt3|=2-sqrt3`
`9a)M=(15/(sqrt6+1)+4/(sqrt6-2)-12/(3-sqrt6))(sqrt6+11)`
`M=((15(sqrt6-1))/(6-1)+(4(sqrt6+2))/(6-4)-(12(3+sqrt6))/(9-6))(sqrt6+11)`
`M=(3(sqrt6-1)+2(sqrt6+2)-4(3+sqrt6))(sqrt6+11)`
`M=(3sqrt6-3+2sqrt6+4-12-sqrt6))(11+sqrt6)`
`M=(4sqrt6-11)(11+sqrt6)`
`M=44sqrt6+24-121-11sqrt6`
`M=33sqrt6-97`
`b)N=(1-(5+sqrt5)/(sqrt5+1))((5-sqrt5)/(sqrt5-1)-1)`
`N=(1-(sqrt5(sqrt5+1))/(sqrt5+1))((sqrt5(sqrt5-1))/(sqrt5-1)-1)`
`N=(1-sqrt5)(sqrt5-1)`
`N=-(sqrt5-1)^2=-(6-2sqrt5)=2sqrt5-6`
