1.x+y=4,x²-y²=20,则x-y=多少?2.已知x+y=3,xy=2,求x²+y
已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y²
1.x+y=4,x²-y²=20,则x-y=多少?2.已知x+y=3,xy=2,求x²+y
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y (4xy-2y²)/4
已知x+y=1,xy=-二分之一,求x(x+y)(x-y)-x(x+y)²
已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
已知非零有理数x,y满足x²-4xy+4y²=0,求x-y/x+y-y-x/x+y的值.
已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}
已知实数x,y满足x²+y²-xy+2x-y+1=0 求x y
已知x-3y=0,求(x²-2xy+y²/x-y)-2y的值
已知X²+3XY-4Y²=0(Y≠0)求X-Y/X+Y