若|x-y-1|+(2x-3y+4)²=0,则x= ,y=

x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? 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2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 若实数x,y满足4^x+4^y=2^(x+1)+2^(y+1),则S=2^x+2^y的取值范围 1.（3x-y)^2-3x+y2.(2a+s)^2-6(2a+s)+93.4(x-y)^2+4(x-y)+14.(4x^2+1)^2-16x^25.(x-y)^3+2×(y-x)^26.4(3a+2x)^2-9(a-x)^27.y-x+3(x-y)^2 x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8) 先化简 再求值 (2x-y)(y+x)-(x-2y)(2y+x)-(-3y+x)^2其(√x+1)+y^2+4=-4y 若实数x,y满足2x*X+3y*y=1,S=3x*x-2y*y,则S的取值范围为叩谢…… 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 1/(x-y)+1/(x+y)+2x/(x^2+y^2)+4x^3/(x^4+y^4)化简 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若1≤x*x+y*y≤4,则试求x*x-2*x*y+3*y*y的取值范围急！！！！！！！！！！！！！！（今晚就要） 若实数x、y满足2x^2+3y^2=1,s=3x^2-2y^2,则S的取值范围是