thực hiện phép tính a) 1/2 . ( 2/9 + 3/7 – 5/27 ) b) 1/3 . 5/7 – 7/27 . 36/14

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1. `a,`

   `1/2 . (2/9 + 3/7 – 5/27)`

   `= 1/2 . (41/63 – 5/27)`

   `= 1/2 . 88/189`

   `= (1.88)/(2.189)`

   `= 244/189`

   `b,`

   `1/3 . 5/7 – 7/27 . 36/14`

   `= 5/21 – 2/3`

   `= 5/21 – 14/21`

   `= (5 – 14)/21`

   `= (-3)/7`

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2. `a)` `1/2` `.` `( 2/9 + 3/7 – 5/27 )`

   `1/2` `.` `( 42/189 + 81/189 – 35/189 )`

   `1/2` `.` `88/189`

   `88/378`

   `44/189`

   `b)` `1/3` `.` `5/7`  `-` `7/27` `.` `36/14`

   `5/21` `-` `7/27` `.` `18/7`

   `5/21` `-` `126/189`

   `45/189` `-`  `126/189`

   `-3/7`

   $#UMR#$

    

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