y=3x、y=1/x和y=-1/3x,这三个哪个是是增函数?

y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 (x-2y)(x+y)-2x(-2x-3y)+6x(-x-y),其中x=-1,y=2要讲解和答题 {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 y'=(x-y+1)/(x+y-3)通解 2(x+y)-3(x-y)=1 6(x+y)+(x-y)=51 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 变量x,y满足约束条件,x+y>=3,x-y>=-1,2x-y 二元一次方程 ：2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 (x-y)^2+(x+y)(x-y) 其中 X =3 Y=-1 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 解方程组3(x+y)-4(x-y)=4和(x+y)/2+(x-y)/6=1kkkkkkkk (2x-2y)/3-(x-y)=-1和6(x+y)-4(2x-y)=16 2x+4y=3 -3x-2y=1 ..求x和y 解方程组,(x+y)^2-3(x+y)=0和x-y=1 已知X和Y满足3X+4Y=2,X-Y-1/7