首先x^6+y^6=(x^2)^3+(y^2)^3 设a=（x^2) b=(y^2) 则,原式= a^3+b^3 =a^3-a^2b+ab^2+a^2b-ab^2+b^3(添项)同上

【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) (x+y)(x-y)+(x-y)^2-(6x^2×y÷2y-2xy^2÷2y)其中x=-3,y=1/3 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y [2(x-y)^5-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2[2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2 3y/x*x-y*y+x/x*x-2xy+y*y+6y*y/x*x*x-x*x*y-xy*y+y*y*y等于多少?