thực hiện phép tính J= 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45

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thực hiện phép tính
J= 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45

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Arya 3 tháng 2021-09-08T16:57:10+00:00 2 Answers 6 views 0

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    0
    2021-09-08T16:58:16+00:00

    Đáp án + Giải thích các bước giải:

    J =` 1/3 + 1/6 + 1/10 + 1/15 + 1/21 + 1/28 + 1/36 + 1/45`

    J = `2/6 + 2/12 + 2/20 + 2/30 + 2/42 + 2/56 + 2/72 +2/90`

    J  = `2/2.3 + 2/3.4 + 2/4.5+ 2/5.6  +2/6.7 + 2/7.8 + 2/8.9 + 2/9.10`

    J = `2.(1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + 1/6 – 1/7 + 1/7 – 1/8 + 1/9 – 1/10)`

    J = `2 . (1/2 – 1/10)`

    J = `2 .  (5/10 – 1/10)`

    J = `2 . 2/5`

    J = `4/5`

    0
    2021-09-08T16:59:02+00:00

    Đáp án:

    `= 4/5`

    Giải thích các bước giải:

    `J=1/3+1/6+1/10+1/15+1/21+1/28+1/36+1/45`

    `= 2/6 + 2/12 + 2/20 + 2/30 + 2/42 + 2/56 + 2/72 + 2/90`

    `= 2 . (1/6+1/12+1/20+1/30+1/42+1/28+1/72+1/90)`

    `= 2 . (1/(2.3)+1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)+1/(7.8)+1/(8.9)+1/(9.10))`

    `= 2 . ( 1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10 )`

    `= 2 . ( 1/2-1/10 ) = 2 . 2/5 = 4/5`

     

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