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

Toán Lớp 5: Bai 8: Tính: a, 1/(1 x 2) + 1/(2 x 3 ) + 1/(3 x 4 ) +1/(4 x 5 )+ -.+ 1/(9 x 10 )

Toán Lớp 5: Bai 8: Tính:
a, 1/(1 x 2) + 1/(2 x 3 ) + 1/(3 x 4 ) +1/(4 x 5 )+ …..+ 1/(9 x 10 )

Comments ( 2 )

  1. Giải đáp+Lời giải và giải thích chi tiết:
    1/(1 xx 2) + 1/(2 xx 3 ) + 1/(3 xx 4 ) +1/(4 xx 5 )+ …..+ 1/(9 xx 10 )
    =1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+…..+1/9-1/10
    =1-1/10
    =10/10-1/10
    =9/10

  2. 1/{1 × 2} + 1/{2 × 3} + 1/{3 × 4} + 1/{4 × 5} + …. + 1/{9 × 10}
    = 1/1 – 1/2 + 1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + … + 1/9 – 1/10
    = 1/1 + 1/2 – 1/2 + 1/3 – 1/3 + 1/4 – 1/4 + 1/5 – 1/5 + .. + 1/9 – 1/9 – 1/10
    = 1/1 + 0 + 0 + 0 + 0 + .. + 0 – 1/10
    = 1/1 – 1/10
    = 10/10 – 1/10
    = 9/10
    #dtkc
     

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