请问（2x－3y－1)×(2x+3y+1）等于多少?

请问（2x－3y－1)×(2x+3y+1）等于多少? x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 3x(2x＋y)－2x(x-y),其中x＝1,y=1/5 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 已知x－y＝1,y≠0,求｛(x＋2y)²＋（2x＋y）(x＋4y)－3(x＋y）（x－y)｝÷y的值. (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 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 (Y-X)^3*(X-Y)^m+(X-Y) ^m+1*(Y-X)^2 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 ｜x＋2y＋3｜＋（2x＋y）2＝0请问x－y＝? 请问 0=-5x+y-1 与 1=4x-3y+2 x*y的值是多少 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 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=?