（X+Y)(X-2Y+4)=0和（x-y-2)(2x-y)=0交点个数,要过程啊~~~为什么要舍去呢

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 {x+2y+2=0 {7y-4y=-41 求X和Y x+2y+2=0 7x-4y=-41 求x和y x*x+2x+y*y-4y+5=0 x= y= 已知5x-4y=0,求x:y和x+y:y的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 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 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 先化简再求值{(x-y)(x+y)-(x+y)(x-2y)}/y 其中xy的值是代数式{(3x-2y-7)^2+|2x+3y先化简再求值{(x-y)(x+y)-(x+y)(x-2y)}/y 其中x和y的值是代数式{(3x-2y-7)^2+|2x+3y+4|}^0无意义 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x-4y)(2x+y)= 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 （X+Y)^2 X^2Y+XY^2注：*/* 是分数 matlab y=[ ]; x=0:0.1:2; y=[y,cos(x)]; plot(x,y) 其中y=[ ]和y=[y,cos(x)]; 啥意 x*x+y*y-2x+4y+5=0求x, 已知x^2+y^2+13-4x+6y=0,求(2x-y)^2-2(2x-y)(x+2y)+(x+2y)^2 .先化简再求值：（2x+y）（2x+y)-(2x-y)平方其中X,Y满足X平方+Y平方-2X+4Y+5=0 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=?