当 x < 0 时
-x > 0
f(-x) = (-x)³+ (-x) + 1
= - x³ - x + 1
因为f(x)是R上的奇函数
所以f(x) = -f(-x) = x³ + x - 1 , f(0) = 0
所以
f(x) = x³ + x + 1 x > 0
= 0 x = 0
= x³ + x - 1 x < 0
当 x < 0 时
-x > 0
f(-x) = (-x)³+ (-x) + 1
= - x³ - x + 1
因为f(x)是R上的奇函数
所以f(x) = -f(-x) = x³ + x - 1 , f(0) = 0
所以
f(x) = x³ + x + 1 x > 0
= 0 x = 0
= x³ + x - 1 x < 0