如何算出f(x)=x³-4x²-4x+16 的 possible rational root

如何算出f(x)=x³-4x²-4x+16 的 possible rational root
如何算出f(x)=x³-4x²-4x+16 的 possible rational root

如何算出f(x)=x³-4x²-4x+16 的 possible rational root
f(x)=x³-4x²-4x+16
=x³+8-4(x²+x-2)
=(x+2)(x²-2x+4)-4(x+2)(x-1)
=(x+2)(x²-6x+8)
=(x+2)(x-2)(x-4)
令f(x)=0
得 x=-2,x=2,x=4