3X＋2Y=－1,X－3Y=7,X＝?Y＝?

3x(2x＋y)－2x(x-y),其中x＝1,y=1/5 3X＋2Y=－1,X－3Y=7,X＝?Y＝? 设x,y满足x＋3y＋|3x－y|＝19,2x＋y＝6则X= Y= 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 把6x（x－y）的平方＋3（y－x）的立方分解因式我知道答案是6x(x-y)^2+3(y-x)^3=6x(x-y)^2-3(x-y)^3=3(x-y)^2[2x-(x-y)]=3(x-y)^2(x+y)可为什么=6x(x-y)^2-3(x-y)^3=3(x-y)^2[2x-(x-y)] 3x＝4y,则x/y=( ),y－x/y＝( ) 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 把(x+y),(x-y)个作为一个整体合并同类项1,7(x+y)-2(x+y)-4(x+y)+2(x+y)2,(x-y)²＋2(x-y)－(x-y)－2(x-y)² 已知x－y＝1,y≠0,求｛(x＋2y)²＋（2x＋y）(x＋4y)－3(x＋y）（x－y)｝÷y的值.