※ 引述《adamchi (adamchi)》之銘言：
: X^4+(1-m)X^3-2X^2+3mx-2m>0，x>1或x<-2，求m範圍為何？
: 答：0<=m<4
: 請問為什麼有等號
(x-1)(x+2)>0 => x^2+x-2>0
(x^2+x-2)(x^2+ax+b) = x^4+(1-m)x^3-2x^2+3mx-2m > 0
=> b = m, a = -m
=> x^2-mx+m > 0 無實數解
=> (-m)^2 - 4m < 0 => 0 < m < 4
m = 0 => (x^2+x-2)(x^2-mx+m) = x^2(x^2+x-2) > 0 => (x^2+x-2) > 0 => x>1或x<-2
m = 4 => (x^2+x-2)(x^2-4x+4) = (x-2)^2(x^2+x-2) > 0
=> (x^2+x-2) > 0 => x>1或x<-2
0≦m≦4
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