1) 3/5 . 1/7 + 3/5 . 7/6 – 2/5

Question

1) 3/5 . 1/7 + 3/5 . 7/6 – 2/5 2) 2/3 . 1/9 + 2/3 . 8/9 – 5/3 3) 1/2 – 5/2 + -7/10

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Kim Cúc 9 months 2021-05-10T12:53:40+00:00 2 Answers 12 views 0

Answers ( )

    0
    2021-05-10T12:55:02+00:00

    `1` 

    `3/5 . 1/7 + 3/5 . 7/6 – 2/5`

    `= 3/5×(1/7+6/7)-2/5`

    `= 3/5×1-2/5=1/5`

    `2` 

    `2/3 . 1/9 + 2/3 . 8/9 – 5/3`

    `=2/3×(1/9+8/9) – 5/3`

    `=2/3×1-5/3=-3/3=-1`

    `3` 

    `1/2 – 5/2 + -7/10`

    `=-4/2-7/10`

    `=-20/10-7/10=-27/10`

    0
    2021-05-10T12:55:28+00:00

    Đáp án:

    `a)` `27/70`

    `b)` `-1`

    `c)` `(-27)/10`

    Giải thích các bước giải:

    `a)` `3/5*1/7+3/5*7/6-2/5`

    `=3/5*(1/7+7/6)-2/5`

    `=3/5*55/42-2/5`

    `=11/14-2/5`

    `=27/70`

    —————–

    `b)` `2/3 * 1/9 + 2/3 * 8/9 – 5/3  `

    `=2/3*(1/9+8/9)-5/3`

    `=2/3-5/3`

    `=-1`

    —————–

    `c)` `1/2 – 5/2 + -7/10`

    `=1/2-5/2-7/10`

    `=(-2)-7/10`

    `=(-27)/10`

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