Question

Answer 1

Câu `5:`

Xét `1/[|x-1|] > 2`    `ĐK: x \ne 1`

`<=>1/[|x-1|]-2 > 0`

`<=>[1-2|x-1|]/[|x-1|] > 0`

  Với `x \ne 1<=>|x-1| > 0`

  `=>1-2|x-1| > 0`

`<=>|x-1| < 1/2`

`<=>-1/2 < x-1 < 1/2`

`<=>1/2 < x < 3/2`

  `=>A=(1/2;3/2)`

`=>R \\ A=(-oo;1/2]uu[3/2;+oo)`

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Câu `6:`

`C_R A=[-3;\sqrt{7})=>A=(-oo;-3)uu[\sqrt{7};+oo)`

`C_R B=(-5;2)uu(\sqrt{3};\sqrt{13})=>B=(-oo;-5]uu[2;\sqrt{3}]uu[\sqrt{13};+oo)`

    Có: `A nn B=(-oo;-5]uu[\sqrt{13};+oo)`

 `=>C_R (A nn B)=(-5;\sqrt{13})`