Question

已知f(x+1/x)=x^2+1/x^2+1/x则f(x)

Answer 1

题目是f(x+1/x)还是f[(x+1)/x]，这种题令x+1/x=t，求出x=~t，带入即可

追问

呵呵，你令个我看看

Answer 2

令x+1/x=t,解得x=[t±√（t²-4）]/2 1/x=2/[t±√（t²-4）]
t²=x²+1/x²+2 x²+1/x²=t²-2
f(t)=t²-2+2/[t±√（t²-4）]