X-Y=4,X^2-y^2=12.则XY等于?

x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 函数f(xy,x+y)=x^2+xy+y^2,则df(x,y)=? f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 若|x-3|+（y+2）=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 若|x-3|+（y+2）²=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 （-3x^y+2xy)-( )=4x^+xy 计算：[(x-y)^2-(x+y)^2]/(-4xy)= 2x^+xy-y^-4x+5y-6=? x^2-xy=4,y^2-xy=9.则x^2-y^2=? 已知x/y=3/4 ,则3xy-2y/2x+4xy=? x-y/x+y=2,则xx+2xy+yy/4xy=? 若x-y/x+y=2,则x2+2xy+y2/4xy=多少 已知x-y=8 xy=7,则3xy-2x+2y+4(y-x)²=? 若(2x-14xy-2y)除以(x-2xy-y)=4,则1/x-1/y= 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 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