giải theo cách lớp 7

`#0409`

`7.`

`a,`

`(-3)/2-2x+3/4=-2`

`-2x=3/2-3/4-2`

`-2x=3/4-2`

`-2x=-5/4`

`x=5/8`

Vậy `x=5/8`

`b,`

`(-2)/3x-3/5=2/5`

`(-2)/3x=2/5+3/5`

`(-2)/3x=1`

`x=-3/2`

Vậy `x=-3/2`

`c,`

`x/2-(3/5-13/5)=-(7/5-7/10)`

`x/2-(-2)=-7/10`

`x/2+2=-7/10`

`x/2=-7/10-2`

`x/2=-27/10`

`10x=-54`

`x=-27/5`

Vậy `x=-27/5`

`d,`

`(3/2-2/(-5)) : x=(-38)/5`

`19/10 : x=(-38)/5`

`x=19/10 : (-38)/5`

`x=-1/4`

Vậy `x=-1/4`

`8.`

`a,`

`(-3)^3+125 . [(3/4)^3 : (5/4)^3]`

`=-27+125 . (3/4 : 5/4)^3`

`=-27 +125 . (3/5)^3`

`=-27+125 . 27/125`

`=-27+27`

`=0`

`b,`

`2^3+3 . (1/2)^0-1+[(-2)^2 : 1/8]-9`

`=8+3 . 1-1+[4 : 1/8]-9`

`=8+3-1+32-9`

`=11-1+32-9`

`=10+32-9`

`=42-9`

`=33`