1)
4x^2-y^2+2x-y
=(2x+y)(2x-y)+(2x-y)
=(2x-y)(2x+y+1)
2)
A^4+A^3+A+1
=A^3(A+1)+A+1
=(A^3+1)(A+1)
=(A+1)(A^2+A+1)(A+1)
=(A+1)^2*(A^2+A+1)
3)
X^4Y+2X^3*Y^2-X^2Y-2XY^2
=X^2*Y(X^2-1)+2XY^2(X-1)
=X^2*Y(X-1)(X+1)+2XY^2(X-1)
=XY(X-1)((X^2+X+2Y)
4、
X^3-8Y^3-X^2-2XY-4Y^2
=(x-2y)(x^2+2xy+4y^2)-(x^2+2xy+4y^2)
=(x-2y-1)(x^2+2xy+4y^2)
PS:X^3-Y^3=(X-Y)(X^2+XY+Y^2)
5、
X^2+X-Y^2-Y
=(X-Y)(X+Y)+(X-Y)
=(X+Y-1)(X-Y)
6、
AB(X^2-Y^2)+XY(A^2-B^2)
=ABX^2+XYA^2-ABY^2-XYB^2
=AX(BX+AY)-BY(AY+XB)
=(AX-BY)(BX+AY)
7、
X^2-3Y-XY+3X
=X(X-Y)+3(X-Y)
=(X-Y)(X+3)
8、
X^3+2X^2Y-9X-18Y
=X^2(X+Y)-9(X+2Y)
=(X+2Y)(X^2-1)
=(X+2Y)(X+1)(X-1)
9、(Y+2)X^2+(Y+2)X-12Y-24
=(Y+2)(X^2+X)-12(Y+2)
=(Y+2)(X^2+X-12)
=(Y+2)(X-3)(X+4)
10、M^2*X^2+N^2Y^2-M^2Y^2-N^2X^2
=M^2*(X^2-Y^2)-N^2*(X^2-Y^2)
=(X^2-Y^2)(M^2-N^2)
(X+Y)(X-Y)(M+N)(M-N)
11、以知X-2Y=-2,B=-4098,求：26*X^2-86XY+8B*Y^2的值
X-2Y=-2,B=-4098,
取x=0,y=1
26X^2-86XY+8B*Y^2
带入x=0,y=1,B=-4098
=8*-4098
=-32784
