若(x-2)^2+(y-1)^2=0,则-x^2y+2xy=

若x+y=1,x不等于0则x+(2xy+y^2)/x/(x+y)/x= 若x,y满足|x-y+1|+(x+y+3)^2=0则x^2-y^2= 若x,y满足|2x-y-3|+|3x+2y+1|=0,则x= y= 若|x+y+1|+(x-2y)的平方=0,则x+2y=? 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若实数X,Y满足X²+Y²+4X-2Y +1=0,则X²-6X+Y²-2Y的最大值是多少 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 若y=x(x-1)(x-2)(x-3),则y′（0）= 若|x+y-1|+（x-y-2)²=0,求代数式（x+2y)(x-2y）-（2x-y)(-y-2x)的值. 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 若|x-2y+1|+|x+y-5|=0,则2^2+y^2 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 若变量x y 满足约束条件y=1 x+y=0 x-y-2=0 则z=2x-y的最大值是多少 若根号x+y-1+(y+3)^2=0,则x+y的平方根是? (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. 若2x-5y=0,则y：x