f(x)为奇函数
f(-x)=-f(x)
(m2-1)X^2-(m+1)x+n+2=-(m2-1)X^2-(m+1)x-n-2
2(m²-1)x²+2(n+2)=0
m²-1=0
n+2=0
m=±1,n=-2