tim x biet a, 1/3-|5/4-2x|=1/4 b, 1/2-|x+1/5|=1/3 c, 3/4-|2x+1|=7/8 d, 2|2x-3|=1/2 e, 7,5-3|5-2x|=-4,5

Bởi

tim x biet
a, 1/3-|5/4-2x|=1/4
b, 1/2-|x+1/5|=1/3
c, 3/4-|2x+1|=7/8
d, 2|2x-3|=1/2
e, 7,5-3|5-2x|=-4,5

0 bình luận về “tim x biet a, 1/3-|5/4-2x|=1/4 b, 1/2-|x+1/5|=1/3 c, 3/4-|2x+1|=7/8 d, 2|2x-3|=1/2 e, 7,5-3|5-2x|=-4,5”

  1. Đáp án:

    `a, 1/3-|5/4-2x|=1/4`

    `|5/4-2x| = 1/3-1/4=1/12`

    `Th1 : 5/4-2x = 1/12`

             `2x = 7/6`

             `x = 7/12`

    `Th2: 5/4 – 2x = -1/12 `

    ` 2x = 4/3 `

    `x = 2/3`

    Vậy `x ∈ { 2/3 ; 7/12 }`

    `b, 1/2-|x+1/5|=1/3`

    `|x+1/5| = 1/6`

    `Th1 : x+1/5 = 1/6`

              `x = -1/30`

    `Th2 : x+1/5 = -1/6`

    `x = -11/30` 

    Vậy `x ∈ { -1/30 ; -11/30}` 

    `c, 3/4-|2x+1|=7/8`

    `|2x+1| = -1/8`

    `=> 2x+1 = -1/8`

    ` 2x = -9/8`

    `x = -9/16`

    Vậy `x ∈ { -9/16 }`

    `d, 2|2x-3|=1/2`

    `|2x-3| = 1/4`

    `Th1 : 2x-3 = 1/4`

    ` 2x = 13/4`

    `x = 13/8`

    `Th2 : 2x-3 = -1/4`

    `2x = 11/4`

    `x =11/8`

    Vậy `x ∈ { 13/8 ; 11/8}`

    `e, 7,5-3|5-2x|=-4,5`

    ` 3|5-2x| = 12`

    `=> |5-2x| = 4`

    ` Th1 : 5-2x = 4`

    `2x = 1`

    `x = 1/2=0,5`

    `Th2: 5 – 2x = -4`

    `2x = 9`

    `x = 9/2`

    Vậy `x ∈ {9/2, 0,5}`

     

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