(X-2Y-1)(2Y-X-1)= (a+1)的平方（a-1）的平方（a方+1）的平方=

已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 A={(X,Y)|X+Y>=1},B={(X,y)|X^2+y^2=1},B={(X,y)|X^2+y^2 A={(x,y)|y=-x^2+mx-1},B={(x,y)|y=3-x,0A={(x,y)|y=-x^2+mx-1},B={(x,y)|y=3-x,0 已知集合A={(x,y)|2x-y+2>=0,x-2y+1 方程组{ X+Y=1 X-Y=2a }的解满足 {x>0 y 集合A={（x,y)|y=-x^2+mx-1},B={(x,y)|y=3-x,0 2y(x+二分之一y)-[(x+y)(x-y)+2y(y+x)],其中|x-1|=2 （x-y)(x+y)-(x+y)^2+2y(y-x),其中x=1,y=3. 1、(-y^3)^5/y^3/ y^2+2(-y)^102、(x-y)^7/(y-x)^6+(x+y)^3/(x+y)^23、已知X^a=5,x^b=3,求X^(3a-2b)的值 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 (x/2y)^2*y/2x-x/y^2/2y^2/x(x/x+y+2y/x+y)*xy/x+2y/(1/x+1/y)(1/a+1/b)^2/(1/a^2-1/b^2) [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 已知x属于R,y>0,集合A={x|x*x+x+1,-x,-x-1},集合B={-y,-y/2,y+1}若A=B,则x*x+y*y的值为 x+2y=2x+y+1=7x-y 求：2x-y? 设x,y满足约束条件x+y>=1,x-y>=-1,2x-y 设x,y满足约束条件x+y>=1,x-y>=-1,2x-y 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2