Đáp án + Giải thích các bước giải:
` 1) `
`a)` `8/15 + (-7)/18 - 13/90`
`= 48/90 + (-35)/90 + (-13)/90`
`= 13/90 + (-13)/90`
`= 0`
`b) 2/7 + 5/7 . 14/25`
`= 2/7 + 2/5`
`= 10/35 + 14/35`
`= 24/35`
`c)` `4 1/3 . 4/9 + 13 2/3 . 4/9`
`= (4 1/3 + 13 2/3) . 4/9`
`= [(4 + 13) + (1/3 + 2/3)] . 4/9`
`= [17 + 1] . 4/9`
`= 18 . 4/9`
`= 8`
`d) 5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 14/11`
`= 5/7 . (5/11 + 2/11 - 14/11)`
`= 5/7 . (7/11 + (-14)/11)`
`= 5/7. (-7)/11`
`= (-5)/11`
`e) (3 1/3 + 2,5) : (3 1/6 - 4 1/5) - 11/31`
`= (10/3 + 5/2) : (19/6 - 21/5) - 11/31`
`= (20/6 + 15/6) : (95/30 + (-126)/30) - 11/31`
`= 35/6 : (-31)/30 - 11/31`
`= 35/6 . (-30)/31 - 11/31`
`= (-175)/31 + (-11)/31`
`= (-186)/31 = -6`
`f)` `6 5/12 : 2 3/4 + 11 1/4. (1/3 - 1/5)`
`= 77/12 : 11/4 + 45/4. (5/15 + (-3)/15)`
`= 77/12 . 4/11 + 45/4. 2/15`
`= 7/3 + 3/2`
`= 14/6 + 9/6`
`= 23/6`
`g) 5/4 - 5/8 + (-2)/3`
`= 10/8 + (-5)/8 + (-2)/3`
`= 5/8 + (-2)/3`
`= 15/24 + (-16)/24`
`= (-1)/24`
`h) 9/7. (3/7 - 1/2)`
`= 9/7. (6/14 + (-7)/14)`
`= 9/7 . (-1)/14`
`= (-9)/98`
`i) 6 1/5. (-2/7) + 14 4/5 . (-2/7)`
`= (-2/7). (6 1/5 + 14 4/5)`
`= (-2/7). [(6 + 14) + (1/5 + 4/5)]`
`= (-2/7). [20 + 1]`
`= (-2)/7 . 21`
`= -6`
`j) 19 5/8 : 7/12 - 15 1/4 : 7/12`
`= (19 5/8 - 15 1/4) : 7/12`
`= [(19 - 15) + (5/8 - 1/4)] : 7/12`
`= [4 + (5/8 + (-2)/8)] : 7/12`
`= [4 + 3/8] : 7/12`
`= [32/8 + 3/8] : 7/12`
`= 35/8 : 7/12`
`= 35/8 . 12/7`
`= 15/2`
`k)` `[6 + (1/2)^3 - |-1/2|] : 3/12`
`= [6 + 1/8 - 1/2] : 3/12`
`= [48/8 + 1/8 + (-4)/8] : 3/12`
`= [49/8 + (-4)/8] : 3/12`
`= 45/8 . 12/3`
`= 45/2`
`l)` `(3 - 2 1/3 + 1/4) : (4 - 5 1/6 + 2 1/4)`
`= (3 - 7/3 + 1/4) : (4 - 31/6 + 9/4)`
`= (36/12 + (-28)/12 + 3/12) : (48/12 + (-62)/12 + 27/12)`
`= (8/12 + 3/12) : ((-14)/12 + 27/12)`
`= 11/12 : 13/12`
`= 11/12 . 12/13`
`= 11/13`
CHÚC BẠN HỌC TỐT!
