câu 1)
a) `-7/25 . 11/13 + -7/25 . 2/13 - 18/25`
= `-7/25. (11/13+2/13)-18/25`
= `-7/25. 1 - 18/25`
=`-7/25-18/25`
`=-1`
c)
`5 2/5` x `4 2/7` + `5 5/7` x `5 2/5`
= `27/5` x `30/7` + `40/7` x `27/5`
= `27/5 x ( `30/7` + `40/7`)
= `27/5` x `10`
`=54`
b)
`5/7 . 1/3 - 5/7 . 1/4 - 5/7 . 1/12`
= `5/7 . ( `1/3-1/4-1/12)
`=5/7. 0`
`= 0`
d)
`75%-1 1/2 +0,5 : 5/12 - (-1/2)²`
= `3/4 - 3/2 + 1/2 . 12/5 - 1/4
= `3/4` - 3/2 + 6/5 - 1/4`
`=(3/4-1/4) - ( 3/2-6/5)`
`= -1 - 3/10`
= `-13/10`
