(2x+y)2.(2x-y)2= (2n+3n)2-(6n+9n)= 要求有过程（2X+Y）^2*(2X-Y)^2=??(2^n+3^n)^2-(6^n+9^n)=??

x^n*y*(-x^2y^m) m(x-y)^n+n(y-x)^2n因式分解 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 S=(x+1/y)+(x^2+1/y^2)+.+(x^n+1/y^n) (y-x)^2n×(x-y)^n-1(x-y)= y=1/(x^2-x),求y^(n) 用列举法表示 集合{x|x=(-1)^n,n∈N}{y|y=-x^2+6,x∈N,y∈N}{(x,y)|y=-x^2+6,x∈N,y∈N} x^n+x^n-1y+x^n-2y^2+.+x^2y^n-2 +xy^n-1 +y^n=多少? (x+y)(m+n)2-(x+y)(m+n)2 若[-3(x+y)^m*(x-y)^2n]^2*[-(x+y)^2]=-a(x+y)^10*(x-y)^12-n,求m,n的值 n(x+y)=xy 怎么化成：(x-n)(y-n)=n^2 计算：（x^2n-2x^ny^n+y^2n)/(x^n-y^n)（n为正整数）= 已知M=(x,y)|y>=x2 N=(x,y)|x2+(y-a)2 y^2-9(x+y)^2.a(x-y)-b(y-x)+c(x-y)..x（m+n)-y(n+m)+(m+n)..(x+y)^2-16(x-y)^2因式分解 假设集合U={(x,y)|x∈R,y∈R },A={(x,y)|2x-y+m>0},B={(x,y)|x+y-n x+y=m,x-y=n,那么2x-3y等于 x+y=m,x-y=n,那么2x-3y等于多少 集合N=｛（x,y)|（x-1）^2｝+(y-1)^20},M={(x,y)|x^2+y^2