Tìm số nguyên x biết :

a) x – 1 / 4 = -4 / x – 1

b) -1 / 6 = 3 / 2 . x

c) 4 / 5 = -12 / 9 – x

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Tìm số nguyên x biết :

a) x – 1 / 4 = -4 / x – 1

b) -1 / 6 = 3 / 2 . x

c) 4 / 5 = -12 / 9 – x

Cứu pé

Answers ( 1 )

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    Đáp án+Giải thích các bước giải:

    `a)( x – 1) / 4 = -4 / (x – 1)`

    `⇒(x-1)(x-1) =-4.4`

    `⇒(x-1)^2 =-16`

    `⇒(x-1)^2 =4^2`

    `TH1:x-1=4`

    `⇒x=4+1`

    `⇒x=5`

    `TH2:x-1=-4`

    `⇒x=-4+1`

    `⇒x=-3`

    Vậy `x=5` hoặc `x=-3`

    `b) -1 / 6 = 3 /2  . x`

    `⇒x=(-1.2)/(6.3)`

    `⇒x=-1/9`

    Vậy `x=-1/9`

    `c) 4 / 5 = (-12 )/ (9 – x)`

    `⇒4(9-x)=-12.5`

    `⇒36-4x=-60`

    `⇒4x=36+60`

    `⇒4x=96`

    `⇒x=96:4`

    `⇒x=24`

    Vậy `x=24`

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