5^2/1.6 + 5^2/6.11 +…..+ 5^2/26.31(tính nhanh) x + 3/10 = 4/5 2/9 – 3.x = -4/3 (3/5 – x ) + 13/20 = 5/6 (2x – 1/2) =3/4

Question

5^2/1.6 + 5^2/6.11 +…..+ 5^2/26.31(tính nhanh)
x + 3/10 = 4/5
2/9 – 3.x = -4/3
(3/5 – x ) + 13/20 = 5/6
(2x – 1/2) =3/4

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Madeline 3 tuần 2021-07-09T22:18:37+00:00 2 Answers 2 views 0

Answers ( )

    0
    2021-07-09T22:19:47+00:00

    1. `5^(2)/1.6+5^(2)/6.11+…+5^(2)/26.31`

    `=5.[(1-1/6)+(1/6-1/11)+…+(1/21-1/26)+(1/26-1/31)]`

    `=5.(1-1/31)`

    `=5.30/31`

    `=150/31`

    2. `x+3/10=4/5`

    `<=>x=4/5-3/10`

    `<=>x=1/2`

    Vậy `x=1/2`

    3. `2/9-3.x=-4/3`

    `<=>-3.x=-4/3-2/9`

    `<=>-3.x=-14/9`

    `<=>-3x=14/27`

    Vậy `14/27`

    4. `(3/5-x)+13/20=5/6`

    `<=>3/5-x=11/60`

    `<=>x=11/60-3/5`

    `<=>-5/12`

    Vậy `-5/12`

    5. `2x-1/2=3/4`

    `<=>2x=5/4`

    `<=>x=5/8`

    Vậy `x=5/8`

    `#Study well`

    0
    2021-07-09T22:19:53+00:00

    Đáp án:

     

    Giải thích các bước giải:

     `a) 5. (5/(1. 6)+ 5/(6. 11)+…+ 5/(26. 31))`

    `= 5. (1- 1/6+ 1/6- 1/11+…+ 5/26- 5/31)`

    `= 5. (1- 1/31)`

    `= 5. 30/31`

    `= 150/31`

    `b) x+ 3/10= 4/5`

    `x= 4/5- 3/10`

    `x= 8/10- 3/10`

    `x= 5/10`

    `x= 1/2`

    `c) 2/9- 3. x= -4/3`

    `3. x= 2/9- (-4/3)`

    `3. x= 2/9- (-12/9)`

    `3. x= 14/9`

    `x= 14/9: 3`

    `x= 14/9. 1/3`

    `x= 14/27`

    `(3/5- x)+ 13/20= 5/6`

    `(3/5- x)= 5/6- 13/20`

    `(3/5- x)= 50/60- 39/60`

    `(3/5- x)= 11/60`

    `x= 3/5- 11/60`

    `x= 36/60- 11/60`

    `x= 25/60`

    `x= 5/12`

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

    `2x= 3/4+ 1/2`

    `2x= 3/4+ 2/4`

    `2x= 5/4`

    `x= 5/4: 2`

    `x= 5/4. 1/2`

    `x= 5/8`

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