3x-2y-7z=0，x-5y2z=0xyz不等於0x：y：z

97年数一解答题求解,谢谢各位设直线L:x+y+b=0,{x+ay-z-3=0在平面π上,而平面π与曲面z=x2+y2相切于点(1,2,5),求a、b之值.解答是这样的：令F(x,y,z)=x2+y2

已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX..已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX..已知

x+y+z=0,3x-2y-2z=5,y-z=2x-7x+y+z=0,3x-2y-2z=5,y-z=2x-7x+y+z=0,3x-2y-2z=5,y-z=2x-73个式子分别标号（1）（2）（3）（1

1.{x:y:z=3:4:52x+3y-5z=-142.{x-y-z=-13x+5y+7z=114x-y+2z=-13.{x+y=1x+z=02x+y+2z=44.{x-y+z=-32x-y-z=-2

X-Y-Z=0X+Y-3Z=42X-5Y+7Z=21X-Y-Z=0X+Y-3Z=42X-5Y+7Z=21X-Y-Z=0X+Y-3Z=42X-5Y+7Z=21X=11,Y=6.5,Z=4.5X=11,y

已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z已知4x-3y-6z=0,x+2y-7z=0,求5x+2y-z/2x-3y-10z已知4x-3y-6z=0,x+2y-

已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z的值已知:x+y+z=0,5x-3y-z=0,求:5x-y+z/2x+8y+7z的值已知:x+y+z=0,5x-3y-z=0

已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值已知x+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值已知x+4y+3z=3x-2y-5z=0,求

三元一次方程解1.{x+y-z=5{3x+2y+z=2{2x-2y+z=-31.{x+y-z=52.{9x-5y+x=-63.{x-y=34.{x+y=35.{4x-2y+z=7{3x+2y+z=2{

证明：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中x,y,z>0证明：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中x,y,z>0证明：x/(y+z)+y/(z+x)+z

已知x-y=4,y-z=2,求x^2y+y^2z+z^2x-(xy^2+yz^2+zx^2)的值.已知x-y=4,y-z=2,求x2y+y2z+z2x-(xy2+yz2+zx2)的值.字母后面的数字都

联立方程x+3y-5z=0,2x+4y+7=0,xyz不等於0,则y/x+z/y+x/z=联立方程x+3y-5z=0,2x+4y+7=0,xyz不等於0,则y/x+z/y+x/z=联立方程x+3y-5

已知x+2y-7z=0,3x-5y+z=0,用z的代数式分别表示x,y,则y=x=已知x+2y-7z=0,3x-5y+z=0,用z的代数式分别表示x,y,则y=x=已知x+2y-7z=0,3x-5y+

如果x/2=y/7=z/5,x,y,z都不等于0,则（x+y+z)/(3x-y)等于多少?如果x/2=y/7=z/5,x,y,z都不等于0,则（x+y+z)/(3x-y)等于多少?如果x/2=y/7=

已知x、y、z满足{x-2y+z=0;7x+4x-5z=0,求x:y:z的值.已知x、y、z满足{x-2y+z=0;7x+4x-5z=0,求x:y:z的值.已知x、y、z满足{x-2y+z=0;7x+

已知x,y,z大于0,x+y+z=2,求证xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3已知x,y,z大于0,x+y+z=2,求证xz/y(y+z)+zy/x(x+y)+yx

三元一次方程：x+y-z=0x+2y+z=132x-3y+2z=5x+y-z=0x+2y+z=132x-3y+2z=5三元一次方程：x+y-z=0x+2y+z=132x-3y+2z=5x+y-z=0x

2x+z=10x+y-z=43x-y-z=02x+z=10x+y-z=43x-y-z=02x+z=10x+y-z=43x-y-z=0x+y-z=43x-y-z=0两式相加4X-2Z=42X-Z=2Z=

方程组(1)x+2y-3z=12x-3y+2z=-13x-y-z=0(2)x+y=z5x-y+z=182x+5y+3z=-1方程组(1)x+2y-3z=12x-3y+2z=-13x-y-z=0(2)x

(1)X+Y=15,Y+Z=-6,Z+X=7.(2)X+Y=-14,Y+Z=-7,Z+X=9.(3)X+Y=0,Y+Z=-1,Z+X=-1.(1)X+Y=15,Y+Z=-6,Z+X=7.(2)X+Y=