bài 3)
`a) 1 2/5 . 2/5 + 25% - 0,7 : 6/5`
`= 7/5 . 2/5 + 1/4 - 7/10 . 5/6`
`= 14/25 + 1/4 - 7/12`
`= 168/300 +75/300 - 175/300`
`=68/300`
`= 17/75`
----------------------------------------
`b) -7/13 . 2/11 + \frac{-7}{13} + 9/11 + 1 7/13`
`= \frac{-7}{13} . ( 2/11 + 9/11) + 20/13`
`= \frac{-7}{13} , 1 + 20/13`
`= \frac{-7}{13} + 20/13`
`= 1`
-----------------------------------------
`c) ( 8 5/11 + 19 4/13 ) - ( 9 4/13 - 1 6/11)`
`= 8 5/11 + 19 4/13 - 9 4/13 + 1 6/11`
`= ( 8 5/11 + 1 6/11) + ( 19 4/13 - 9 4/13)`
`= 10 + 10`
`= 20`
------------------------------------------------
`d) 6 3/8 - ( 4 3/8 - 1/2)`
`= 6 3/8 - 4 3/8 + 1/2`
`= ( 6 3/8 - 4 3/8) + 1/2`
`= 2 + 1/2`
`= 5/2`
`e) 2 1/2 . 1,5 - ( 11/10 + 50%) : 4/15`
`= 5/2 . 3/2 - 8/5 . 15/4`
`= 15/4 - 6`
`= -9/4`
---------------------------------------------
bài 4)
`a) 3/2 + x= \frac{-5}{3}`
`x =\frac{-5}{3} - 3/2`
`x = -19/6`
-----------------------------------------
`b) 5 2/3 - (2/3 + x) = 4 1/3`
`17/3 - ( 2/3 + x ) = 13/3`
`(2/3 + x) = 17/3 - 13/3`
`2/3 + x = 4/3`
`x = 4/3 - 2/3`
`x = 2/3`
-------------------------------------------
`c) | x - 1/2| + 75%= 9/10`
`| x - 1/2| = 9/10 - 75/100`
`|x - 1/2 | = 3/20`
⇒ `x - 1/2 = 3/20` hoặc `x - 1/2 = -3/20`
`x = 3/20 + 1/2` hoặc `x = -3/20 + 1/2`
`x = 13/20` hoặc `x = 7/20`
Vậy `x∈ {13/20 ;7/20}`
---------------------------------------------------------
`d) | 2 : x - 4/3| : 4/15 - 75%= 9 1/4`
`|2 : x - 4/3| : 4/15 - 3/4 = 37/4`
`|2 : x - 4/3| : 4/15 = 37/4 + 3/4`
`|2 : x - 4/3| : 4/15 = 10`
`|2 : x - 4/3| = 10 . 4/15`
`|2 : x - 4/3| = 8/3`
⇒ `2: x - 4/3 = 8/3` hoặc `2 : x - 4/3 = -8/3`
`2 : x = 8/3 + 4/3` hoặc `2 : x = -8/3 + 4/3`
`2 : x = 4 hoặc `2 : x = -4/3`
`x = 2 : 4 hoặc `x = 2 :-4/3 `
`x = 1/2` hoặc `x = -3/2`
