若{4x+5y=2 ① 5x+4y=7 ② 则{ x+y=___ x-y=____ 解之得:｛x=_____ y=_____若{4x+5y=2 ① 5x+4y=7 ② 则{ x+y=___ x-y=____ 解之得:｛x=_____ y=_____

若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 x*x+2x+y*y-4y+5=0 x= y= 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 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)= 3(x-y)把(x-y)看作一个整体,化解:5(x-y)+2(x-y)-4(x-y)=3(x-y)²-4(x-y)+7(x-y)-6(x-y)²= 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 5x-4y(y-x)=? 把(x-y)看做一个整体,合并同类项5(x-y)+2(x-y)-4(x-y)=3(x-y)次方-4(x-y)+7(x-y)-6(x-y)次方= 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 解方程组 x+y/5+x-y/2=7 4(x+y)-5(x-y)=2 方程2分之x+y+2分之x-y=7,4(x+y)-5(x-y)=2 若5x+3y=3x+4y=x+2y+6,则x+y=___ 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 解方程组x+y/2+x-y/2=7,4(x+y)-5(x-y)=2... 大括号x+y/2+x-y/3=11/6 4(x+y)-5(x-y)=7 快