若5x+6y=13,7x+18y=—1,的解也是方程2x-ay=18的一个解,则a=什么

{6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 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 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 (1)7x+3y=18 2x+3y=13 (2)5x+2y=7 2x+y=1 (3)3x+4y=5 4x+5y=6如题 解这些方程组 (1) 7x-2y=96 5x-3y=45 (2) 4x+2y=50 2x+3y=47 (3) 4x+2y=66 7x-3y=70(4) 11x+9y=49 13x-3y=17 (5) 2y-x=1 13x-8y=59 (6) 18x+29y=307 16x+28y=284 解下列不等式组用加减法1.{3x+5y=-2 3x-y=4 2.{x-2y=8 3x+2y=163.{二分之三x+2y=1 二分之三x-y=-54.{3x-2y=8 3x+2y=165.{5x+6y=13 7x+18y=-16.{二分之一x+3y=7 2x-5y=-6 5x+6y-11=13 7x+18y=-1解方程打错是5x+6y=13 7x+18y=-1 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 (x+y)/6+(x-y)/10=1,(x+y)/6-(x-y)/10=5 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 解二元一次方程{5X-2y=3 X+6y=7 {5x+4y=-3 2x-3y=8 {x+Y+Z=26 x-Y=1 2x-Y+z =18{x/3+Y/5=3 X/2- 2Y/5=1 快 1 .{5X-2y=3 X+6y=7 2.{5x+4y=-3 2x-3y=8 3.{x+Y+Z=26 x-Y=1 2x-Y+z =18 4.{x/3+Y/5=3 X/2- 2Y/5=1 y-x/7-x+y/6=1/2 5(x+y)-2(y-x)=1怎么解答 解方程组6(x-y)-7(x+y)=21 2(x-y)-5(x+y)=-1 是两元一次方程组｛6(x-y)-7(x+y)=212(x-y)-5(x+y)=-1 若5x+y/7x+10y=1/2,则x/y=? 若7x+10y分之5x+y=1/2,则x/y= 若（5x+y）／(7x+10y)=1/2则x/y= 6（x-y)-7(xy)=21,2(x-y)-5(x+y)=-1