地下城天界城市在那里:3个式子,2x+y=15,x+2y>20,x+2y<25.求y的值.在线等答案

3个式子,2x+y=15,x+2y>20,x+2y<25.求y的值. 3个式子,2x+y=15,x+2y>20,x+2y<25.求y的值.在线等答案 (x-y)^2×(y-x)^3=??? 1/4(x+y)+1/2(x+y)*(x+y)>=x*根号y+y*根号x 若 x/3y = y/2x-5y =6x-15y/x 下列式子不能用平方差计算公式算的是A(x-y-z)(-x+y+z) B(-2x+3y)(3y+2x) C(x+y+z)(x-y+z) D(-5-X)(X-5 （x-y)^3*(x-y)^2*(y-x) 3X(X-Y)+2Y(X-Y) x,y满足:3x+8y+15>=0&5x+3y-6<=0&2x-5y+10>=0,求x－y的最大、最小值 已知x,y的方程组(x-y=a 3,2x y=5)的解满足x>y>0,化简|a| |3 a|