若x+y=7,xy=12,求(x+y)^2,x^2+y^2,(x-y)^2的值

若x^2+xy+y=14,y^2+xy+x=28,求x+y x+y=12 xy=9 求x y 若x+y=4,x^3+y^3=(x+y)(x^2-xy+y^2)z,求x^3+12xy+y^3的值. 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y |x|/x+y/|y|+xy/|xy|= x^2+xy=12,xy+y^2=15,求(x+y)^2-(x+y)(x-y) x+y=4,xy=－12,求x^+y^,x^-xy+y^实际求：x平方＋y平方和x平方－xy＋y平方 已知x+y=6,xy=7,试求x*x+y*y,x*x-y*y的值 x,y都是自然数,且x(x-y)-y(y-x)=12,求x+y-xy的值 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 已知x-xy =21,xy-y=-12,分别求式子x-y与x-2xy +y 1/x-1/y=x,求5y+xy-5y/y-xy-x=? 若(y-x)/xy=3,求分式(2x+3xy-2y)/(x-2xy-y)的值 若y-x/xy=3,求分式2x+3xy-2y/x-2xy-y 若xy=2（x+y),求 （3x-5xy+3y)÷(-x+3xy-y) 的值 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=?