C) 6 và 1/5.(-2/7)+14 và 4/5.(-2/7) D) 7 và 1/6. (-7/6)+10 và 5/6.(-7/6) E) 5/7.5/11+5/7.2/11-5/7.14/11 Ai làm nhanh mk vote 5star.

Question

C) 6 và 1/5.(-2/7)+14 và 4/5.(-2/7)
D) 7 và 1/6. (-7/6)+10 và 5/6.(-7/6)
E) 5/7.5/11+5/7.2/11-5/7.14/11
Ai làm nhanh mk vote 5star.

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Thạch Thảo 9 months 2021-04-27T09:55:02+00:00 2 Answers 8 views 0

Answers ( )

    0
    2021-04-27T09:56:05+00:00

    `a) 6 1/5 .(-2)/7 + 14 4/5 .(-2/7)`
    ` = (-2)/7 .(6 1/5 + 14 4/5)`
    ` = (-2)/7 .[ (6+14) + (1/5 + 4/5)]`
    ` = (-2)/7 . (20 +1)`
    ` = (-2)/7 . 21`
    `b) 7 1/6 .(-7)/6 + 10 5/6 .(-7)/6`
    ` = (-7)/6 .( 7 1/6 + 10 5/6)`
    ` = (-7)/6 . [(7+10) + (1/6+5/6)]`
    ` = (-7)/6 . (17 + 1)`
    ` = (-7)/6 . 18`
    `c) 5/7 . 5/11 + 5/7 . 2/11- 5/7. 14/11`
    ` = 5/7. (5/11 + 2/11 – 14/11)`
    ` = 5/7 . (-7)/11`

    `f) 19 5/8: 7/12- 15 1/4:7/12`
    ` = 19 5/8 . 12/7 – 15 1/4 . 12/7`
    ` = 12/7 .( 19 5/8 – 15 1/4)`
    ` = 12/7. [(19-15) + (5/8-1/4)]`
    ` = 12/7. (4 + 3/8)`
    ` = 12/7 . 4 3/8`

    `g) 2/5. 1/3- 2/15 : 1/5+ 3/5. 1/3`
    ` = 2/5 . 1/3 – 2/15 . 5 + 3/5 . 1/3`
    ` = 2/5 . 1/3 – 2/3 + 3/5 . 1/3`
    ` =2/5 . 1/3 – 2.1/3 + 3/5 . 1/3`
    ` = 1/3.(2/5 – 2 +3/5)`
    ` =1/3. (-1)`

    `h) 4/9. 19 1/3- 4/9. 39 1/3`
    ` = 4/9.(19 1/3 – 39 1/3)`
    ` = 4/9 . [(19 -39) + (1/3-1/3)]`
    ` = 4/9 . (-20)`

    0
    2021-04-27T09:56:25+00:00

    Giải thích các bước giải:

    `a) 6 1/5 .(-2)/7 + 14 4/5 .(-2/7)`

    ` = (-2)/7 .(6 1/5 + 14 4/5)`

    ` = (-2)/7 .[ (6+14) + (1/5 + 4/5)]`

    ` = (-2)/7 . (20 +1) = (-2)/7 . 21`

    $\\$
    `b) 7 1/6 .(-7)/6 + 10 5/6 .(-7)/6`

    ` = (-7)/6 .( 7 1/6 + 10 5/6)`

    ` = (-7)/6 . [(7+10) + (1/6+5/6)]`

    ` = (-7)/6 . (17 + 1)= (-7)/6 . 18`

    $\\$

    `c) 5/7 . 5/11 + 5/7 . 2/11- 5/7. 14/11`

    ` = 5/7. (5/11 + 2/11 – 14/11) = 5/7 . (-7)/11`

    $\\$

    `f) 19 5/8: 7/12- 15 1/4:7/12`

    ` = 19 5/8 . 12/7 – 15 1/4 . 12/7`

    ` = ( 19 5/8 – 15 1/4).12/7 `

    ` =  [(19-15) + (5/8-1/4)].12/7`

    ` = (4 + 3/8).12/7=  4 3/(8) . 12/7`

    $\\$

    `g) 2/5. 1/3- 2/15 : 1/5+ 3/5. 1/3`

    ` = 2/5 . 1/3 – 2/15 . 5 + 3/5 . 1/3`

    ` = 2/5 . 1/3 – 2/3 + 3/5 . 1/3`

    ` =2/5 . 1/3 – 2.1/3 + 3/5 . 1/3`

    ` = 1/3.(2/5 – 2 +3/5) =1/3. (-1)`

    $\\$

    `h) 4/9. 19 1/3- 4/9. 39 1/3`

    ` = 4/9.(19 1/3 – 39 1/3)`

    ` = 4/9 . [(19 -39) + (1/3-1/3)] = 4/9 . (-20)`

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