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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 5: 1/5 + 1/45 + 1/117 +–…+1/49 x 53

Home/ Toán Lớp 5: 1/5 + 1/45 + 1/117 +–…+1/49 x 53

Toán Lớp 5: 1/5 + 1/45 + 1/117 +–…+1/49 x 53

Tháng Tư 3, 2023 Toán học 1 Comment 0 views

Toán Lớp 5: 1/5 + 1/45 + 1/117 +………..+1/49 x 53

Comments ( 1 )

  1. ngoclanquynh
    ngoclanquynh
    3 Tháng Tư, 2023 at 7:54 chiều
    Reply
    1/5+1/45+1/117+. . .+$\dfrac{1}{49×53}$ 
    =$\dfrac{1}{1×5}$+$\dfrac{1}{5×9}$+$\dfrac{1}{9×13}$+. . .+$\dfrac{1}{49×53}$
    =1/4.($\dfrac{4}{1×5}$+$\dfrac{4}{5×9}$+$\dfrac{4}{9×13}$+. . .+$\dfrac{4}{49×53}$)
    =1/4.(1-1/5+1/5-1/9+1/9-1/13+. . .+1/49-1/53)
    =1/4.(1-1/53)
    =1/4. 52/53
    =13/53

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222-9+11+12:2*14+14 = ? ( )

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