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

Toán Lớp 4: ài 5 tính nhanh : 4/25*1/3+4/15*13/5-1/15*4*4/5

Toán Lớp 4: ài 5 tính nhanh : 4/25*1/3+4/15*13/5-1/15*4*4/5

Comments ( 2 )

  1. Giải đáp:
     
    Lời giải và giải thích chi tiết:
     $\frac{4}{25}*\frac{1}{3}+\frac{4}{15}*\frac{13}{5}-\frac{1}{15}*4*\frac{4}{5}$
    $=\frac{4}{25}*\frac{1}{3}+\frac{1}{3}*\frac{4}{5}*\frac{13}{5}-\frac{1}{3}*\frac{4}{5}*\frac{4}{5}$
    $=\frac{1}{3}*(\frac{4}{25}+\frac{4}{5}*\frac{13}{5}-\frac{4}{5}*\frac{4}{5})$
    $=\frac{1}{3}*[\frac{4}{5}(\frac{1}{5}+\frac{13}{5}-\frac{4}{5})]$
    $=\frac{1}{3}*\frac{4}{5}*\frac{10}{5}$
    $=\frac{4}{15}*2$
    $=\frac{8}{15}$

  2. 4/25 xx 1/3 + 4/15 xx 13/5 – 1/15 xx 4 xx 4/5
    = 1/5 xx 4/5 xx 1/3 + 4/15 xx 13/5 – ( 1/15 xx 4) xx 4/5
    = 1/5 xx ( 4/5 xx 1/3) + 4/15 xx 13/5 – 4/15 xx 4/5
    =  1/5 xx 4/15 + 4/15 xx 13/5 – 4/15 xx 4/5
    = ( 1/5 + 13/5 – 4/5) xx 4/15
    = 2 xx 4/15
    = 8/15
    #caty09

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

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