Giúp tôi với Đề:A) 5/12 x 2/5 + 3/5 x 5/12 = B)3/4 x 6/7 – 1/4 x 6/7=

2 bình luận về “Giúp tôi với Đề:A) 5/12 x 2/5 + 3/5 x 5/12 = B)3/4 x 6/7 – 1/4 x 6/7=”

1. a)

   5/12xx2/5+3/5xx5/12

   =5/12xx(2/5+3/5)

   =5/12xx5/5

   =5/12xx1

   =5/12

   b)

   3/4xx6/7-1/4xx6/7

   =(3/4-1/4)xx6/7

   =2/4xx6/7

   =1/2xx6/7

   =6/14=3/7

   #Wang

    

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2. Giải đáp:

    a)

   \frac{5}{12}xx\frac{2}{5}+\frac{3}{5}xx\frac{5}{12}

   =\frac{5}{12}xx(\frac{2}{5}+\frac{3}{5})

   =\frac{5}{12}xx\frac{5}{5}

   =\frac{5}{12}xx1

   =\frac{5}{12}

   b)

   \frac{3}{4}xx\frac{6}{7}-\frac{1}{4}xx\frac{6}{7}

   =\frac{6}{7}xx(\frac{3}{4}-\frac{1}{4})

   =\frac{6}{7}xx\frac{2}{4}

   =\frac{6}{7}xx\frac{1}{2}

   =\frac{3xx2xx1}{7xx2}

   =\frac{3}{7}

   #DYNA

    

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