Đáp án+Giải thích các bước giải:
`a)(sqrt{0,25}-sqrt{225}+sqrt{2,25}):sqrt{169}`
`=(sqrt{25/100}-sqrt{15^2}+sqrt{225/100}):sqrt{13^2}`
`=(5/10-15+15/10):13`
`=(2-15):13`
`=-13:13`
`=-1`
`e)E=sqrt{(sqrt7-5)^2}+sqrt7`
`=|sqrt7-5|+sqrt7`
Do `sqrt7<sqrt{25}=5`
`=>sqrt7-5<0`
`=>|sqrt7-5|=5-sqrt7`
`=>E=5-sqrt7+sqrt7`
`=5`
`g)G=sqrt{(2-3sqrt3)^2}+sqrt{(8-3sqrt3)^2}`
`=|2-3sqrt3|+|8-3sqrt3|`
Vì `2=sqrt{4}<sqrt{27}<sqrt{64}`
`=>2<3sqrt3<8`
`=>3sqrt3-2>0,8-3sqrt3>0`
`=>|2-3sqrt3|=3sqrt3-2,|8-3sqrt3|=8-3sqrt3`
`=>G=3sqrt3-2+8-3sqrt3`
`=6`
