简算:(1998×1999)分1998+(1999×2000)分1998+(2000× 2001)分1998……+(20
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简算:(1998×1999)分1998+(1999×2000)分1998+(2000× 2001)分1998……+(2049×2050)分1998=
![简算:(1998×1999)分1998+(1999×2000)分1998+(2000× 2001)分1998……+(20](/uploads/image/z/2723944-40-4.jpg?t=%E7%AE%80%E7%AE%97%EF%BC%9A%281998%C3%971999%29%E5%88%861998%EF%BC%8B%EF%BC%881999%C3%972000%EF%BC%89%E5%88%861998%EF%BC%8B%EF%BC%882000%C3%97+2001%EF%BC%89%E5%88%861998%E2%80%A6%E2%80%A6%EF%BC%8B%EF%BC%8820)
(1998×1999)分1998+(1999×2000)分1998+(2000× 2001)分1998……+(2049×2050)分1998
=1998((1/1998-1/1999)+(1/1999-1/2000)+(1/2000-1/2001)+.+(1/2049-1/2050))
=1998(1/1998-1/2050)
=1-1998/2050
=52/2050
=26/1025
=1998((1/1998-1/1999)+(1/1999-1/2000)+(1/2000-1/2001)+.+(1/2049-1/2050))
=1998(1/1998-1/2050)
=1-1998/2050
=52/2050
=26/1025