M=(x+1)²/[x²+1]
=[x²+2x+1]/[x²+1]
=1+2x/[x²+1]
1、若x=0,则M=1;
2、若x≠0,则:M=1+2/[x+1/x] =====>>>>>>> 考虑到 x+1/x≥2【若x>0】或x+1/x≤-2【若x
M=(x+1)²/[x²+1]
=[x²+2x+1]/[x²+1]
=1+2x/[x²+1]
1、若x=0,则M=1;
2、若x≠0,则:M=1+2/[x+1/x] =====>>>>>>> 考虑到 x+1/x≥2【若x>0】或x+1/x≤-2【若x