Bài 1:
`A=3/4-5/6+1-2/3`
`=9/12-10/12+12/12-8/12`
`=(9-10+12-8)/12`
`=3/12`
`=1/4`
`B=3/5(5/2-10/3)+5/3:10/9`
`=3/5 . 5/2-3/5 . 10/3+5/3 . 9/10`
`=3/2-2+3/2`
`=(3/2+3/2)-2`
`=6/2-2`
`=3-2`
`=1`
`C=(2/3)^2 .(3/4)^2`
`=(2/3 . 3/4)^2`
`=(1/2)^2`
`=1/4`
`D=(8^8 .3^14)/(9^6 .2^20)`
`=((2^3)^8 .3^14)/((3^2)^6 .2^20)`
`=(2^24 .3^14)/(3^12 .2^20)`
`=2^4 .3^2`
`=16.9`
`=144`
Bài 2:
`a)2/3-x=3/4`
`x=2/3-3/4`
`x=8/12-9/12`
`x=-1/12`
Vậy `x=-1/12`
`b)5/12x=1/4`
`x=1/4:5/12`
`x=1/4 . 12/5`
`x=3/5`
Vậy `x=3/5`
