Đáp án:
d, `(8 - 9/4 + 2/7) - (-6 - 3/7 + 5/4) - (3 + 2/4 - 9/7)`
` = 8 - 9/4 + 2/7 + 6 + 3/7 - 5/4 - 3 - 2/4 + 9/7`
` = (8 + 6 - 3) - (9/4 + 5/4 + 2/4) + (2/7 + 3/7 + 9/7)`
` = 11 - 4 + 2`
` = 9`
e, `1/3 - 3/5 + 5/7 - 7/9 + 9/11 - 11/13 + 13/15 + 11/13 - 9/11 + 7/9 - 5/7 + 3/5 - 1/3`
` = (1/3 - 1/3) - (3/5 - 3/5) + (5/7 - 5/7) - (7/9 - 7/9) + (9/11 - 9/11) - (11/13 - 11/13) + 13/15`
` = 0 - 0 + 0 - 0 + 0 - 0 + 13/15`
` = 13/15`
f, `1/2014 - 1/(2014 . 2013) - 1/(2013. 2012) - ..... - 1/(3.2) - 1/(2.1)`
` = 1/2014 - ( 1/(2014 . 2013) + 1/(2013.2012) + .... + 1/(2.3) + 1/(1.2) )`
`= 1/2014 - ( 1 - 1/2 + 1/2 - 1/3 + .... + 1/2012 - 1/2013 + 1/2013 - 1/2014)`
`= 1/2014 - (1 - 1/2014)`
`= 1/2014 - 2013/2014`
`= -2012/2014 = -1006/1007`