HELP ME: a)7/19.8/11+7/19.3/11+12/19 b)17/13.18/23-4/13.18/23- -5/23 c)5/7.-4/19+-15/7.5/19

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1. Đáp án:

    

   Giải thích các bước giải:

   `7/19. 8/11+7/19. 3/11+12/19`

   `= 7/19. (8/11 + 3/11) + 12/19`

   `= 7/19. 1 + 12/19`

   `= 7/19 + 12/19`

   `=1`

   `17/13. 18/23 – 4/13. 18/23- (-5)/23`

   `= 18/23. (17/13 – 4/13) + 5/23`

   `= 18/23. 1 + 5/23`

   `= 18/23 + 5/23`

   `=1`

   `5/7. -4/19+ -15/7. 5/19`

   `= -20/133 + -75/133`

   `= -5/7`

   Trả lời

2. Đáp án:

   a) `1`

   b) `1`

   c) `-5/7`

   Giải thích các bước giải:

   a) `7/19 . 8/11+7/19 . 3/11+12/19`

   `= 7/19 . (8/11 + 3/11) + 12/19`

   `= 7/19 . 1 + 12/19`

   `= 7/19 + 12/19 = 1`

   b) `17/13 . 18/23 – 4/13 . 18/23- (-5)/23`

   `= 18/23 . ( 17/13 – 4/13 ) + 5/23`

   `= 18/23 . 1 + 5/23`

   `= 18/23 + 5/23 = 1`

   c) `5/7 . (-4/19) + (-15/7) . 5/19`

   `= 5/7 . (-4/19) + 5/7 . (-3) . 5/19`

   `= 5/7 . [ (-4/19) + (-3) . 5/19 ]`

   `= 5/7 . (-1) = -5/7`

   Trả lời