Cau a bai 1 va cau a bai 2.

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Cau a bai 1 va cau a bai 2.
cau-a-bai-1-va-cau-a-bai-2

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Dulcie 5 years 2021-05-22T15:15:27+00:00 1 Answers 24 views 0

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  1. bonexptip
    0
    2021-05-22T15:17:18+00:00
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    Đáp án:

     `A={3+\sqrt{3}}/6`

    `P=-3-2\sqrt{3}`

    Giải thích các bước giải:

     Bài 1

    `a)` `A=1-{\sqrt{x}}/{\sqrt{x}+1}` $(x\ge 0)$

    `A={\sqrt{x}+1-\sqrt{x}}/{\sqrt{x}+1}`

    `A=1/{\sqrt{x}+1}`

    Ta có: `x=7-4\sqrt{3}`

    `<=>x=2^2-2.2.\sqrt{3}+3`

    `<=>x=(2-\sqrt{3})^2`

    `<=>\sqrt{x}=2-\sqrt{3}`

    `=>A=1/{2-\sqrt{3}+1}=1/{3-\sqrt{3}}`

    `<=>A={3+\sqrt{3}}/{(3-\sqrt{3}).(3+\sqrt{3})}`

    `<=>A={3+\sqrt{3}}/{3^2-3}={3+\sqrt{3}}/6`

    $\\$

    Bài 2 

    `a)` ` x=4-2\sqrt{3}`

    `<=>x=3-2.\sqrt{3}.1+1`

    `<=>x=(\sqrt{3}-1)^2`

    `<=>\sqrt{x}=\sqrt{3}-1`

    $\\$

    `P={\sqrt{x}+1}/{\sqrt{x}-1}` $(x\ge 0; x\ne 1)$

    `P={\sqrt{3}-1+1}/{\sqrt{3}-1-1}`

    `P={\sqrt{3}}/{\sqrt{3}-2}`

    `P={\sqrt{3}.(\sqrt{3}+2)}/{(\sqrt{3}-2).(\sqrt{3}+2)}`

    `P={3+2\sqrt{3}}/{3-4}`

    `P=-3-2\sqrt{3}`

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )