①x^2-xy②x^2-xy+2y^2③x^2+y^2④x²-2xy+y²,能用公式法分解因式的有?

x^2-xy/xy-y^2约分 （x^2+xy/x-y)/（xy/x-y)计算 2x²y-3(2xy-xy)-xy (x^2+2xy+y^2-4xy)*(x^2-2xy+y^2+4xy) ①(9x²y-6xy²)÷3xy ②(3x²y-xy²+2分之1xy)÷(-2分之1xy) .(x+y-2)(x+y-2xy)+(xy-1)^2 (x^2-xy)y÷y-x/xy怎么做? (xy-x²)÷(x²-2xy+y²/xy)×（x-y/x²） x-y/x²÷x²-2xy+y²/xy*（xy-x²） （y/(x^2-xy)+x/(y^2-xy))除以(x-y)/(xy) (-x-y)(x^2+xy+y^2) 化简x^-y^/x^-2xy+y^ 2*(x-y)²(y-x)(xy) 初二数学化简分式x^2 -y^2/xy - xy-y^2/xy-x^2x^2 -y^2/xy - xy-y^2/xy-x^2 3xy(x^2y-xy^2+xy)-xy^2(2x^2-6xy+2x)过程 ((xy+2)(xy-2)-2x²y²+5(xy-y)²)÷(2xy) 计算：3xy(x²y-xy²+xy)-xy²(2x-xy+2x） xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2