Tìm x: (x+5)(x-1)= (x+7)^2

Question

Tìm x:
(x+5)(x-1)= (x+7)^2

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Orla Orla 1 year 2020-10-31T12:44:20+00:00 2 Answers 63 views 0

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    0
    2020-10-31T12:45:20+00:00

    `=> x^2+4x-5=x^2+14x+49`

    `=> 10x +49+5=0`

    `=> 10x = -54`

    `=> x = -5,4`

    0
    2020-10-31T12:45:36+00:00

    Đáp án:

     `x=-27/5`

    Giải thích các bước giải:

     `(x+5)(x-1)=(x+7)^2`

    `⇔x^2-x+5x-5=x^2+2.x.7+7^2`

    `⇔x^2+4x-5=x^2+14x+49`

    `⇔x^2+14x+49-x^2-4x+5=0`

    `⇔10x+54=0`

    `⇔10x=-54`

    `⇔x=-54/10=-27/5`

    vậy `x=-27/5`

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