求y=8/x y=3x y=-4x+5 y=(x*x)-6x+7 这4个函数的定义域和值域y=8/x 定义域为{x|x≠0}值域Ry=3x 定义域R值域Ry=-4x+5 定义域R值域Ry=x²-6x+7=(x-3)²-2 定义域R值域{y|y≥-2}

已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知：4x = 5y,求(x+y) ：y (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) x(x-3y)=4y(x-3y),求x:y 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? |x|=3 |y|=5 |x-y|=|x|+|y| 求 X+Y和 X-Y 等于多少 y=x^3-5x^2+2x-8 求y^2求y撇 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知(3x+1)(3x-3)-3x+2)^2=-7,(y+7)(y-7)-y(y-7)=0,求8y^2-5y(-y+3x)+4y(-4y-5/2x)的值 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 (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuaihuajian 已知2x+2y=-8,4x+y=15求（x-y)^-(3x+2y)^ 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值