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

Toán Lớp 7: CMR 1/1.2+1/3.4+1/5.6+-…+1/49.50=1/26+1/27+1/28+-.+1/50

Tháng Chín 22, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: CMR
1/1.2+1/3.4+1/5.6+…….+1/49.50=1/26+1/27+1/28+…..+1/50

Comments ( 2 )

  1. hienthucthu97
    hienthucthu97
    22 Tháng Chín, 2022 at 7:27 chiều
    Reply
    \text {Mon}
    1/1.2+1/3.4+1/5.6+. . .+1/49.50
    =1-1/2+1/3-1/4+1/5-1/6+. . .+1/49-1/50
    =1+1/2+1/3+1/4+1/5+1/6+. . .+1/49+1/50-2.(1/2+1/4+1/6+. . .+1/50)
    =1+1/2+1/3+1/4+1/5+1/6+. . .+1/49+1/50-(1+1/2+1/3+. . .+1/25)
    =1/26+1/27+1/28+. . . +1/50 (ĐPCM)
     

  2. thanhmaianh
    thanhmaianh
    22 Tháng Chín, 2022 at 7:26 chiều
    Reply
    Giải đáp + Lời giải và giải thích chi tiết:
    Giải:
    1/1.2 + 1/3.4 + 1/5.6 + … + 1/49.50 = 1/26 + 1/27 + … + 1/50
    = 1/1 – 1/2 + 1/3 – 1/4 + … + 1/49 + 1/50
    = (1/1 + 1/3 + … + 1/49) – (1/2 + 1/4 + … + 1/50)
    = (1/1 + 1/2 + 1/3 + … + 1/49 + 1/50) – 2(1/2 + 1/4 + … + 1/50)
    = 1/1 + 1/2 + 1/3 + … + 1/50 – 1 – 1/2 – 1/3 – … – 1/25
    = 1/26 + 1/27 + 1/28 + … + 1/50 (đpcm)
    Chúc bn hok tốt

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

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