f(x)为奇函数
f(x)+f(-x)=0
x
-x>0
f(-x)=(-x)^3 + (-x) +1
=-f(x)
=>
f(x)=x^3 + x -1
而取x=0
f(0)+f(-0)=0
=>f(0)=0
所以
f(x)=
xxx+x+1 (x>0)
0 (x=0)
xxx+x-1 (x