bài1: thực hiện phép tính
a) -1/2 -(-3/4 +0,6) b)-3/4+-2/5- 1/8
c)-3,5- 1 4/3+3/5 d)3/4-[-1/2-(3/5+1/10)
bài2: tìm x
a) -3/4-x=5/6 b) -x-1/2=5/7
c) 2/3x-3/7=1/6 d)1/3- -2/5x=1/10
Đáp án:
`-1/2 -(-3/4 +0,6) `
`=-1/2-(3/4 +6/10)`
`=-1/2 – ( 27/20)`
`=-37/20`
`-3/4+(-2/5)- 1/8`
`=-23/20 – 1/8`
`=-51/40`
`-3,5- 1 4/3+3/5`
`=35/10 – 7/3 + 3/5`
`=7/6 + 3/5`
`=53/30`
`3/4-[-1/2-(3/5+1/10)]`
`=3/4-[-1/2-7/10]`
`=3/4 – 6/5`
`=-9/20`
Bài 2:
a) `-3/4-x=5/6`
`x=-3/4 – 5/6`
`=>x=-19/12`
b) `-x-1/2=5/7`
`-x=17/14`
`x=-17/14`
c) `2/3x-3/7=1/6`
`2/3 x = 1/6 +3/7`
`2/3x= 25/42`
`x=25/28`
d) `1/3- -2/5x=1/10`
`-2/5x= 7/30`
`x=7/30 ÷ -2/5`
`x=-7/12`