当x取何整数值时,能使下式值为正整数.(x^4+x^2-2)/(x^3-x^2+x-1)×(x-1)/(x^3+2x^2+2x+4)×(－2)/(x^3-x-x^2+1)

Question

当x取何整数值时,能使下式值为正整数.
(x^4+x^2-2)/(x^3-x^2+x-1)×(x-1)/(x^3+2x^2+2x+4)×(－2)/(x^3-x-x^2+1)

Answer 1

(x^4+x^2-2)/(x^3-x^2+x-1)×(x-1)/(x^3+2x^2+2x+4)×(－2)/(x^3-x-x^2+1)
=(x^2+2)(x^2-1)/[(x-1)(x^2+1)] * (x-1)/[(x+2)(x^2+2)] * (-2)/[(x-1)(x^2-1)]
= -2/[(x-1)(x^2+1)]
那么当
(x-1)(x^2+1)=正负1或正负2时,表达式取整
分别解得
当(x-1)(x^2+1)=-1时有整数解x=0
故,当x=0时,该式为整数2