(x+2)(x-1)=x平方+mx+n,x^2+MX+N=(X-1)(X+2)=x^2+x-2所以M=1,N=-2,则m+n=-1
(x+2)(x-1)=x^4+mx+n,x^2+mx+n=(x-1)(x+2)=x^2+x-2所以m=1,n=-2得m+n=-1
确定是x的4次方?
令X等于1带入,解得= -1
(x+2)(x-1)=x^2+x-2m+n=-1