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

Toán Lớp 6: 1x2x3+2x3x4+3x4x5+…+n(n+1)(n+2)

Toán Lớp 6: 1x2x3+2x3x4+3x4x5+…+n(n+1)(n+2)

Comments ( 2 )

  1. Chúc bạn học tốt nhé!!!
    Kết quả trên ảnh nhá

    toan-lop-6-123-234-345-n-n-1-n-2

  2. Đặt A = 1×2×3+2×3×4+3×4×5+…+n(n+1)(n+2)
    4A = 1×2×3×4+2×3×4×(5-1)+3×4×5×(6-2)+…+n(n+1)(n+2)((n+3)+(x-1))
    4A = 1×2×3×4+2×3×4×5-1×2×3×4+3×4×5×6-2×3×4×5+…+n(n+1)(n+2)(n+3)-(n-1)n(n+1)(n+2)
    4A = n(n+1)(n+2)(n+3)
    A = (n(n+1)(n+2)(n+3))/4
    (Chúc bạn học tốt)
     

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

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