Đáp án+Giải thích các bước giải:
`a)sqrt{1-4x+4x^2}(x>2)`
`=sqrt{(2x-1)^2}`
`=|2x-1|`
`=2x-1(x>2=>2x>4=>2x-1>3>0)`
`b)sqrt{16x^2-8x+1}(x<1/4)`
`=sqrt{(4x-1)^2}`
`=|4x-1|`
`=1-4x(x<1/4=>4x<1=>4x-1<0)`
`c)sqrt{x^2+6x+9}+sqrt{x^2+8x+16}(x>=0)`
`=sqrt{(x+3)^2}+\sqrt{(x+4)^2}`
`=|x+3|+|x+4|`
`=x+3+x+4`
`=2x+7`
`d)sqrt{a-2-2sqrt{a-3}}-sqrt{a+1-4sqrt{a-3}}(3<=a<=4)`
`=sqrt{a-3-2sqrt{a-3}+1}-sqrt{a-3-4sqrt{a-3}+4}`
`=sqrt{(sqrt{a-3}-1)^2}-sqrt{(sqrt{a-3}-2)^2}`
`=|sqrt{a-3}-1|-|sqrt{a-3}-1|`
`a<=4=>a-3<=1=>\sqrt{a-3}-1<=0,sqrt{a-3}-2<0`
`=>D=1-sqrt{a-3}-2+sqrt{a-3}=-1`
`e)sqrt{(x+4)^2}-sqrt{x^2+8x+16}/(x+4)`
`=|x+4|-sqrt{(x+4)^2}/(x+4)`
`=|x+4|-|x+4|/(x+4)`
`x>=-4`
`=>x+4>=0`
`=>E=x+4-(x+4)/(x+4)=x+4-1=x+3`
`x<=-4`
`=>x+4<=0`
`=>E=-x-4-(-(x+4))/(x+4)=-x-4+1=-x-3`
