5x-6y= -28 ,3x+4y=6求x与y

5x-6y= -28 ,3x+4y=6求x与y x+5y=4 3x-6y=5 求x ,y 已知3X=4X,5Y=6Z求X+Y：Y+Z 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y (-x+6):(x-y);(4x+y)=3;14:1,求x+y的值. 6X+3Y=5(X+Y)求结果 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 6x+5Y=31 2X+3Y=17求X求 Y 已知x^3+xy^2+x+x^2y+y^3+y=0,求5x-6y/3x+4y的值. 已知:3x-5y=0,求x/y,x-y/y,x-y/x 几道 数学题急啊 对了再加20分(x+y)^2-(x+y)^3(x-y)^2-(x-y)^3 (x-y)^2-(y-x)^32(x-y)-3(y-x)^24ab(a+b)^2-6a^2b(a+b)(x+y)(x-y)-(x+y)^28a(x-y)^2-4b(y-x)a=-5 a+b+c=-5.2求代数式a^2(-b-c)-3.2a(c+b)的值 x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y 6x-2y=5 8x-3y=-5 求x,y 6x+5y+3z=100 x+y+z=30 求 x y x平方+y平方-4x-6y+13=0 ,求3x+4y 已知x-2y=2,求4x-y-8分之3x+y-6 已知x*x+y*y-4x-6y+13=0,求3x+4y的值