解不等式x³-3x²+x+1<0借助啊.

问题描述:

解不等式x³-3x²+x+1<0
借助啊.

x³-3x²+x+1
=x³-2x²+x-x²+1
=x(x-1)²-(x-1)(x+1)
=(x-1)[x(x-1)-(x+1)]
=(x-1)(x²-2x-1)
当x-1>0,即x>1时,
x²-2x-1