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

Toán Lớp 6: S=3/1.4+3/4.7+3/7.10+–+3/40.43+3/43.46. A=1/1.4+1/4.7+1/7.10+1/13.16+1/16.19+1/19.22 B=1/6+1/12+1/20+1/30+1/42+1/56+–1/10

Tháng Hai 7, 2023 Toán học 2 Comments 0 views

Toán Lớp 6: S=3/1.4+3/4.7+3/7.10+……..+3/40.43+3/43.46.
A=1/1.4+1/4.7+1/7.10+1/13.16+1/16.19+1/19.22
B=1/6+1/12+1/20+1/30+1/42+1/56+……..1/10
hlep me !

Comments ( 2 )

  1. haiyemy
    haiyemy
    7 Tháng Hai, 2023 at 5:37 sáng
    Reply
    Giải đáp:
    text(S)=3/1.4+3/4.7+3/7.10+…+3/40.43+3/43.46
    =>text(S)=1-1/4+1/4-1/7+1/7-1/10+…+1/40-1/43+1/43-1/46
    =>text(S)=1-1/46
    =>text(S)=45/46
    Vậy text(S)=45/46.
    text(A)=1/1.4+1/4.7+1/7.10+1/10.13+1/13.16+1/16.19+1/19.22
    =>text(3A)=3/1.4+3/4.7+3/7.10+3/10.13+3/13.16+3/16.19+3/19.22
    =>text(3A)=1-1/4+1/4-1/7+1/7-1/10+1/10-1/13+1/13-1/16+1/16-1/19+1/19-1/22
    =>text(3A)=1-1/22
    =>text(3A)=21/22
    =>text(A)=7/22
    Vậy text(A)=7/22.
    text(B)=1/6+1/12+1/20+1/30+1/42+1/56+…+1/110
    =>text(B)=1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+…+1/10.11
    =>text(B)=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+…+1/10-1/11
    =>text(B)=1/2-1/11
    =>text(B)=9/22
    Vậy text(B)=9/22.

  2. maingocquynhnhu2k1
    maingocquynhnhu2k1
    7 Tháng Hai, 2023 at 5:36 sáng
    Reply
    S = 1/( 1 . 4 ) + 3/( 4 . 7 ) + 3/( 7 . 10 ) + …. + 3/( 40 . 43 ) + 3/( 43 . 46 )
    S = 1/1 – 1/4 + 1/4 – 1/7 + 1/7 – 1/10 + …. + 1/40 – 1/43 + 1/43 – 1/46
    S = 1 – 1/46
    S = 45/46
    _____________________________________________________
    A = 1/( 1 . 4 ) + 1/( 4 . 7 ) + …. + 1/( 19 . 22 )
    A . 3 = 3/( 1 . 4 ) + 3/( 4 . 7 ) + …. + 3/( 19 . 22 )
    A . 3 = 1/1 – 1/4 + 1/4 – 1/7 + …. + 1/99 – 1/22
    A . 3 = 1 – 1/22
    A . 3 = 21/22
    A = 21/22 : 3
    A = 7/22
    _____________________________________________________
    B = 1/6 + 1/12 + 1/20 + 1/30 + …. + 1/110
    B = 1/( 2 . 3 ) + 1/( 3 . 4 ) + 1/( 4 . 5 ) + …. + 1/( 10 . 11 )
    B = 1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + …. + 1/10 – 1/11
    B = 1/2 – 1/11
    B = 9/22

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

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