X+3y=12 X+5y=18 怎么算?

X+3y=12 X+5y=18 怎么算? x+x+x+y+y=6.4 y+y+y+x+x=7.1 怎么算? (y-x)(x-y)^3(y-x)^5怎么算 y/(x+y)-x/(x-y)=?怎么算? 二元一次方程(x+y)/2+(x-y)/3=6,4(x+y)-5(x-y)=2怎么算 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=? 请问算到4x/y=3y/x后怎么算出x,y, 5x+4y=22 4x+y=3y+x 怎么解 x=3,y=4,z=5,求以下表达式的值,怎么算 (x && y)==(x || z) (x>y)+(y!=z) || (x+y)&&(y-z) x++ -y+(++z) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) c语言中x=(x=++y,x+5,x/5) x=3 y=4怎么算 X-Y=3 2X+4Y=18 X=? Y=?方程式怎么算呀 (2x+y-1)(2x-y-1)=?和（3x+y-5a）的平方怎么算 3y-0.5=0.5y-x、解是y=-5/3怎么算3y-0.5=0.5y-x、解是y=-5/3 {2X=5(X+Y)3X-10(X+Y)=2怎么解?