已知x^2+xy=13,且xy+y2=12,求(x+y)(x-y)和(x+y)^2
已知x^2+xy=13,且xy+y2=12,求(x+y)(x-y)和(x+y)^2
已知x+y=4,x-y=6,化简xy(y2+y)-y2(xy+2x)-3xy,并求它的值.
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
已知x+y=8,xy=12,求x2+y2;(x-y)2的值
已知x2-2xy=3y2且x,y为非零实数 求:(1)2x+y/x-2y (2)2x2-3y2+5xy/x2+xy+y2
已知:x2+xy=12,xy+y2=15,求(x+y)2-(x+y)(x-y)的值.
已知:x-xy=40,xy-y=-20,求代数式x-y和x+y-2xy的值.
已知x2+y2-2x+4y+5=0,求(x^4-y^4)/(2x^2+xy-y^2)·[(2x-y)/(xy-y^2)]
已知x>y>0,且xy=1,求 (x2+y2)/(x-y)的最小值,
已知x^2+xy=12,且xy+y^2=13,求x^2+y^2
已知xy=3,x2+xy-2y2=2(x+2y),且x≠-2y,则x+y=______.
已知x2-3xy+2y2=10,且x-y=3,求2x-y的值.