因为a是方程x^2-1994x+1=0的一个根
所以a^2-1994a+1=0
a^2=1994a-1
a^2-1993a+1994/(a^2+1)
=1994a-1-1993a+1994/(1994a)
=a+1/a-1
=(a^2+1)/a-1
=1994a/a-1
=1993
因为a是方程x^2-1994x+1=0的一个根
所以a^2-1994a+1=0
a^2=1994a-1
a^2-1993a+1994/(a^2+1)
=1994a-1-1993a+1994/(1994a)
=a+1/a-1
=(a^2+1)/a-1
=1994a/a-1
=1993