1/3x+1/4y=16 1/3y+1/4x=19 帮我,+20.

请帮我做几道方程1、x+2y=0 3x+4y-6=02、3x+2y=-2 3x-y=43、6x+7y=-19 5y-6x 帮我解几道很简单的题{3x+2y=5 {4x-3y=53x-5y=1 4x+6y=14{3x+2y=5 {0.5x-3y {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 帮我做这3道数学题吧解下列方程组(1)5x-3y+z=25x+2y-4y=3-5x+y-z=2(2)x+y=-2x+z= 谁帮我解一下化简题,问题是这样的,化简4（y+1)+4(1-x)-4(x+y),再求值,x=-2,y=3 帮我解这道方程组 3X=5Y 2X-3Y=1 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 帮因式分解谢谢,4(x+y)(x-y)^3-9(x+y)^3(x-y) 9x^2-x+1/16这两题, 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 3分之2(X-Y)-4分之X+Y=-1,6(X+Y)-4(2X-Y)=16