y-7x=49x-y=16

y-7x=49x-y=16 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简 x / y(x+y) - y / x(x+y) = 7x:4y,x:y=( ):( x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 5X+16X= Y+9Y= X+7X-4X= x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=? 解方程组x+y/5+x-y/7=2 3(x+y)+x-y/7=16 y=x(x 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)(x-2y)=-5 (x-y)(x+2y)=7 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 x+2y=2x+y+1=7x-y 求：2x-y? 当x+y=2时7(x+y)一(x+y)+(x+y)=? x^2+y^2=15,x+y=7,x＞y,求x-y 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 方程组 x+5y+2=06x-7y=16x=y=