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

Toán Lớp 5: tính bằng cách thuận tiện : [ 1- 1/2 ] * [ 1- 1/3] * [1-1/4 ]* [ 1-1/5]

Toán Lớp 5: tính bằng cách thuận tiện :
[ 1- 1/2 ] * [ 1- 1/3] * [1-1/4 ]* [ 1-1/5]

Comments ( 2 )

  1. #andy
    \[\begin{array}{l}
    \left( {1 – \frac{1}{2}} \right).\left( {1 – \frac{1}{3}} \right).\left( {1 – \frac{1}{4}} \right).\left( {1 – \frac{1}{5}} \right)\\
     = \left( {\frac{2}{2} – \frac{1}{2}} \right).\left( {\frac{3}{3} – \frac{1}{3}} \right).\left( {\frac{4}{4} – \frac{1}{4}} \right).\left( {\frac{5}{5} – \frac{1}{5}} \right)\\
     = \frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}\\
     = \frac{{1.2.3.4}}{{2.3.4.5}}\\
     = \frac{1}{5}
    \end{array}\]

  2. (1 – 1/2) xx (1 – 1/3) xx (1 – 1/4) xx (1 – 1/5)
    = 1/2 xx 2/3 xx 3/4 xx 4/5
    = frac{1 xx 2 xx 3 xx 4}{2 xx 3 xx 4 xx 5}
    = frac{1}{5}
    Vậy kết quả cuối cùng là 1/5

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