2x+5y=21,x+3y=8怎么解?

3x+2=y 5x+4=y 7x+6=y 9x+8=y 11x=y怎么解 2x+5y=-21,x+3y=8二元一次方程组怎么解 2x+5y=21,x+3y=8怎么解? {2X=5(X+Y)3X-10(X+Y)=2怎么解? 3x*5y+2x*6y=2.7*(3x+2x)怎么解 2x=y 3y=x怎么解 怎么解方程组2x-3y=8 5x-7y=5 3 x+5y =8和2x-y=1这个方程组怎么解 5x+4y=22 4x+y=3y+x 怎么解 X+y=15 2x-y=5y-x怎么解 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 二元二次方程(x+y)(x-2y)=-5,(x-y)(x+2y)=7 怎么解 x+y=480 (x-x/5)*2/3=y-15怎么解 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. (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian 由X/Y=2Y/X-Y 怎么解得x=2y? 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2=