Đáp án:`a)\sqrt{12}`
`=\sqrt{3.4}`
`=2\sqrt3`
Vì `\sqrt7>\sqrt3`
`\sqrt5>\sqrt3`
`=>\sqrt7+\sqrt5>2\sqrt3=\sqrt{12}.`
`b)` Xét `\sqrt8+3-(6+\sqrt2)`
`=\sqrt8-\sqrt2+3-6`
`=2\sqrt2-\sqrt2-3`
`=\sqrt2-3<\sqrt9-3=3-3<0`
`=>\sqrt8+3-(6+\sqrt2)<0`
`=>\sqrt8+3<6+\sqrt2`
`c)12-5\sqrt3-2`
`=10-5\sqrt3`
`=5(2-\sqrt3)>5.(\sqrt3-\sqrt3)=0`
`=>12-5\sqrt3-2>0`
`=>12-5\sqrt3>2`
`d)\sqrt{27}+\sqrt6+1`
`=3\sqrt3+\sqrt6+1`
Vì `\sqrt6>\sqrt3`
`=>\sqrt6+1>\sqrt3`
`=>3\sqrt7+\sqrt6+1>4\sqrt3=sqrt{48}`
