已知x+y=9,x-y=6求(1)x^2+y^2(2)xy

已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知xy=-2,x-y=3,求(x+y)(x-y)-y²+(x-y)²-(6x²y-2xy 已知x+y=9,x-y=6求(1)x^2+y^2(2)xy 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+2(xy+y)的值 已知X+Y=-1,xy=-2,求代数式-5(x+y)+(x-y)+(xy+y)的值 已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值.