Giải thích các bước giải:

`c)`
`1995/1997xx1990/1993xx1997/1994xx1993/1995xx997/995`
`=(\cancel{1995}xx1990xx\cancel{1997}xx\cancel{1993}xx997)/(\cancel{1997}xx\cancel{1993}xx1994xx\cancel{1995}xx995)`
`=(1990xx997)/(1994xx995)`
`=(\cancel{995}xx\cancel{2}xx\cancel{997})/(\cancel{997}xx\cancel{2}xx\cancel{995})`
`=1`
`d)`
`(1-1/2)xx(1-1/3)xx(1-1/4)xx...xx(1-1/1996)`
`=(2/2-1/2)xx(3/3-1/3)xx(4/4-1/4)xx...xx(1996/1996-1/1996)`
`=1/2xx2/3xx3/4xx...xx1995/1996`
`=(1xx\cancel{2}xxcancel{3}xx...xx\cancel{1995})/(\cancel{2}xx\cancel{3}xx\cancel{4}xx...xx\cancel{1995}xx1996)`
`=1/1996`

`c)1995/1997xx1990/1993xx1997/1994xx1993/1995xx997/995` `=(\cancel{1995}xx1990xx\cancel{1997}xx\cancel{1993}xx997)/(\cancel{1997}xx\cancel{1993}xx1994xx\cancel{1995}xx995)`
`=(1990xx997)/(1994xx995)`
`=(\cancel{995}xx\cancel{2}xx\cancel{997})/(\cancel{997}xx\cancel{2}xx\cancel{995})`
`=1`

``
`d)(1-1/2)xx(1-1/3)xx(1-1/4)xx...xx(1-1/1996)` `=(2/2-1/2)xx(3/3-1/3)xx(4/4-1/4)xx...xx(1996/1996-1/1996)`
`=1/2xx2/3xx3/4xx...xx1995/1996`
`=(1xx\cancel{2}xxcancel{3}xx...xx\cancel{1995})/(\cancel{2}xx\cancel{3}xx\cancel{4}xx...xx\cancel{1995}xx1996)`
`=1/1996`