2x-5y=-3 和 5x-2y=-18 怎么写

5X+Y=3 X+5Y=2 求x和y.5X+Y=3X+5Y=2求x和y. 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 3x+2y=5 3y+2x=5 求x和y 5x+y=2,x-3y=4,求x和y, 5x+y=2 x-3y=4 求x和y x+y/2+x-y/6=5 2(x+y)-3(x-y)=-2 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 (计算方程组x+y)/2=6-(x-y)/3,6(x+y)-5(x-y)=18 已知X,Y,满足(X+3Y)(X-3Y)=-10(Y^2-6/5)和2X(Y-1)+4(1/2X-1)=0 （X+Y)^2 X^2Y+XY^2注：*/* 是分数 把(X-Y)和(X+Y)各看作一个字母因式,合并同类项3（X+Y)²-（X-Y)+2(X+Y)²+（X-Y)-5(X-Y)²=2在后面是²,2在前面是与后面相乘.