A) 1 - 1974/1975 = 1/1975
1 - 1998/1999 = 1/ 1999
Mặt khác 1/1975 > 1/1999
=> 1974/1975 < 1998/1999
Ta có 1974/1975 =1-1974/1975=1975/1975-1
974/1975=1/1979.
1998/1999 =1-1998/1999=1999/1999-1998/1999 =1/1999.
Vì 1/1979 l/h 1/1999 nên 1974 /1975 l/h 1998/1999.
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