A-B=1+2X^2-2X^3-X^2
=-2X^3+X^2+1
=-(X-1)(2X^2+X+1)
=(2X^2+X+1)(1-X)
因为2x^2+x+1=2(x+1/4)^2+7/8>0
所以1-x>0,即xB;
1-x=0即x=1时,A=B;
1-x1时,A
A-B=1+2X^2-2X^3-X^2
=-2X^3+X^2+1
=-(X-1)(2X^2+X+1)
=(2X^2+X+1)(1-X)
因为2x^2+x+1=2(x+1/4)^2+7/8>0
所以1-x>0,即xB;
1-x=0即x=1时,A=B;
1-x1时,A