2x-4y=6和3x=2y=17该怎样解

2x-4y=6和3x=2y=17该怎样解 老师y=cos2x和y=cosx的图像该怎样画,2x该怎样取值呢? 解方程组3(x+y)-4(x-y)=4和(x+y)/2+(x-y)/6=1kkkkkkkk 当m等于何值时,关于x.y的方程组：x-y=2m+1和3x+y=2-m的解满足x乘y小于0.这道题该怎样做? {x-y=3 3x-8y=14}该怎样解? (2x-2y)/3-(x-y)=-1和6(x+y)-4(2x-y)=16 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 解二元一次方程组：3(x+y)-4(x-y)=4,x+y/2+x-y/6+1x+y/2+x-y/6+1=1 若x和y满足x^2+y^2=6x-4y-17,则2x-3y的最大值和最小值的和是多少? (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 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= 解方程组 10（x-y)=3(x+y)+15 6(x+y)=4(2x-y)+1610（x-y)=3(x+y)+156(x+y)=4(2x-y)+16 解方程组 10（x-y)=3(x+y)+15 6(x+y)=4(2x-y)+1610（x-y)=3(x+y)+156(x+y)=4(2x-y)+16分开的。