1999×2000-1993/1 x1994-1
= 1999×2000-1993 x1994-1
= 1999×2000-1993 x(2000-6)-1
= 1999×2000-1993 x2000+1993x6-1
【前2项提取公因数2000】
=2000x(1999-1993)+1993x6-1
=2000x6+1993x6-1
【前2项提取公因数6】
=6x(2000+1993)-1
=6x3993-1
=6x(4000-7)-1
=24000-43
=23957
=(2000-1)×2000-1/1993×1993
=4000000-2000-1
=3997999