2. tính bằng 2 cách. a.( 1/3 +2/5 ) x 3/4 b.( 7/9 +2/3 ) :5/6

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1. $#Dino$

   `a) (1/3+2/5)xx3/4`

   `=11/15xx3/4`

   `=11/20`

   Cách 2:

   `(1/3+2/5)xx3/4`

   `=1/3xx3/4+2/5xx3/4`

   `=1/4+3/10`

   `=11/20`

   ……………………

   `b) (7/9+2/3):5/6`

   `=(7/9+2/3)xx6/5`

   `=13/9xx6/5=26/15`

   Cách 2:

   `(7/9+2/3):5/6`

   `=7/9xx6/5+2/3xx6/5`

   `=14/15+4/5`

   `=26/15`

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2. `#Kenshiro`

   `a ) ( 1/3 + 2/5 ) xx 3/4`

   Cách 1 :

   `( 1/3 + 2/5 ) xx 3/4 = 5/15 + 6/15 xx 3/4 = 11/15 xx 3/4 = 33/60 = 11/20`

   Cách 2 :

   `(1/3 + 2/5) xx 3/4 = 1/3 xx 3/4 + 2/5 xx 3/4 = 3/12 + 6/20 = 60/240 + 72/240 = 132/240 = 11/20`

   `b ) ( 7/9 + 2/3 ) : 5/6`

   Cách 1 :

   `( 7/9 + 2/3 ) : 5/6 = 13/9 : 5/6 = 13/9 xx 6/5 = 78/45 = 26/15`

   Cách 2 :
   `( 7/9 + 2/3 ) : 5/6 = ( 7/9 : 5/6 ) + ( 2/3 : 5/6 ) = ( 7/9 xx 6/5 ) + ( 2/3 xx 6/5 ) = 42/45 + 12/15 = 14/15 + 4/5 = 26/15`

    

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