Đáp án + Giải thích các bước giải:
` 5)`
`a)` `1,4 . 15/49 - (4/5 + 2/3) : 2 1/5`
`= 7/5 . 15/49 - (12/15 + 10/15) : 11/5`
`= 3/7 - 22/15 . 5/11`
`= 3/7 - 2/3`
`= 9/21 + (-14)/21`
`= (-5)/21`
`b)` `(-3,2) . (-15)/64 + (0,8 - 2 4/15) : 3 2/3`
`= (-16)/5 . (-15)/64 + (4/5 - 34/15) : 11/3`
`= 3/4 . (12/15 + (-34)/15) . 3/11`
`= 3/4 + (-22)/15 . 3/11`
`= 3/4 + (-2)/5`
`= 15/20 + (-8)/20`
`= 7/20`
`c)` `1 13/15 . (0,5)^2 . 3 + (8/15 - 1 19/60) : 1 23/24`
`= 28/15 . 0,25. 3 + (8/15 - 79/60) : 47/24`
`= 28/15 . 1/4 . 3 + (32/60 + (-79)/60) . 24/47`
`= 7/15 . 3 + (-47)/60 . 24/47`
`= 7/5 + (-2)/5`
`= 1`
`d)` `8 2/7 - (3 4/9 + 4 2/7)`
`= 8 2/7 - 3 4/9 - 4 2/7`
`= (8 2/7 - 4 2/7) - 3 4/9`
`= [(8-4) + (2/7 - 2/7)] - 31/9`
`= [4+0] - 31/9`
`= 4 - 31/9`
`= 36/9 + (-31)/9`
`= 5/9`
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