|a-b| +|a|=_____(化简)x-xy=20,xy-y=-10,x-y=____,x+y-2xy=_____.
分解因式 (1)a^2-9b^2=_____ (2)9x^2y^2+12xy+4_____ (3)a(x-y)-b(y-
若x+y=9,xy=20则 x^2+y^2=_____, (x-y)^2=_____
已知:A=X*X-3xy+y*y,B=2x*x+xy-3y*3y.求A+B,A-B,A+2B
(x-A)*(B-y)=x^2-9xy+8y^2,求A,B
3a-3b/10ab*25a^b3/a^-b^= x^-4y^/x^+2xy+y^/x+2y/2x^+2xy
1、分解因式:xy-x-y+1=_____?
已知A=8x^2y-6xy^2-3xy,B=7xy^2-2xy+5x^2y,
已知A=5x^2y-3xy^2+4xy,B=7xy^2-2xy+x^2y.
已知a=5x的平方y-3xy的平方+4xy,b=7xy的平方-2xy+x的平方y.
A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²+3x-y,若x=
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²-3x-y,若x
设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²+3x-y.若x