Đáp án:
Giải thích các bước giải:
`a)`
`\sqrt{a^4(a^2-6a+9)}`
`=\sqrt{a^4(a-3)^2}`
`=a^2|a-3|`
`=a^2(a-3)` do `a>=3`
`b)`
`\sqrt{27} \sqrt{48(a^2-2a+1)}`
`= \sqrt{27.48(a^2-2a+1)}`
`= \sqrt{1296(a-1)^2}`
`=36|a-1|`
`=36(1-a)` do `a<1`
`c)`
`1/(a-b) \sqrt{a^6(a^2-2ab+b^2)}`
`=1/(a-b) \sqrt{a^6(a-b)^2}`
`=1/(a-b)a^3|a-b|`
`=1/(a-b)a^3(a-b)` Do `a>b>0`
`=a^3`
`d)`
`3/(a-1) \sqrt{(4a^2-8a+4)/25}`
`=3/(a-1) \sqrt{(4(a^2-2a+1))/25}`
`=3/(a-1) \sqrt{(4(a-1)^2)/25}`
`=3/(a-1).(2|a-1|)/5`
`=3/(a-1).(-2(a-1))/5` do `a<1`
`=-6/5`
`e)`
`1/(a-3b) \sqrt{a^6(a^2-6ab+9b^2)}`
`=1/(a-3b) \sqrt{a^6(a-3b)^2}`
`=1/(a-3b) a^3|a-3b|`
`=1/(a-3b) .a^3(a-3b)` do `a<3b<0`
`=a^3`
