Bài `1:`
`a) (-2/7)^2. `
` = (-2)^2/ 7^2`
` = 4/49`
`b) (2 -1/2).(-3/4+1/2).`
` = (4/2 - 1/2).(-3/4 + 2/4)`
` = 3/2 . (-1)/4`
` = (-3)/8`
`c) 21/25. 11/9. 5/7`
` =(21.11.5)/(25.9.7)`
` = (7.3.11.5)/(5.5.3.3.7)`
` = 11/ (5.3)`
` = 11/15`
`d)( 3/29-1/5). 29/3`
` = [(15)/(145) - (29)/(145) ] .29/3`
` = -14/145 . 29/3`
` = -14/15`
Bài `2:`
`a) 8/23 . 46/24 -x =1/3`
`=> 2/3 - x = 1/3`
`=> x =2/3 - 1/3`
`=> x = 1/3`
Vậy `x=1/3`
`b) 1-x = 49/65 . 5/7`
`=> 1-x = 7/13`
`=> x = 1- 7/13`
`=> x = 6/13`
Vậy ` x=6/13`