已知:A=3X^2+5Y^2-2XY^2,B=4X^2-2Y^2+XY^2,求1,A+B.求2,B-A要原因,1,我算出来是7X^4+1,可答案是7X^2+3Y^2-XY^22,我算出来是1-7Y^2+2XY^4,是X^2-7Y^2+3X^2还有XY^2+2XY^2到底等于几啊,是不是次数和次数相乘等于2XY^4

已知A=8x^2y-6xy^2-3xy,B=7xy^2-2xy+5x^2y求A-B 已知xy^2=-2,求-xy（x^2y^5-xy^3-y)的值. 已知xy^2=-2 求-xy(x^2y^5-xy^3-y) 已知xy^2=-2xy(x^2y^5-xy^3-y) 已知x^2-xy=5,xy-y^2=-3求3(x^2-xy)-xy+y^2 已知a=x^+xy+y^ b=-3xy-x^求2A-3B 已知X-XY-2Y=0求2X+3XY-Y/X-2XY+5Y 已知xy/x+y=3,求代数式2x-5xy+2y/x-3xy+y 已知xy/x+y=2,求代数式3x-5xy+3y/-x+2xy-y的值 已知x+y分之xy=2,那么3x-5xy+3y分之3xy-x-y= 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 已知Y-x=3xy,求(5x+3xy-5y)÷(x-2xy-y) 已知X+Y分之XY=2,求-X+3XY-Y分之3X+5XY+3Y 已知xy=2(x+y),求(5x-xy+5y)/(3xy-x-y)的值 已知xy=2(x+y),求5x-xy+5y/3xy-x-y的值 已知x-y=3xy,求5x+2xy-5y/x-4xy-y的值 已知xy/x+y=2,求代数式8x-5xy+8y/-x+3xy-y的值 已知a=5x^2-3xy^2+4xy,b=3xy^2-2xy+x^2y,则a-b=【】