2,x,y,z,18成等比数列,则y=______.
已知实数z、y、z满足x+y=5及z2=xy+y-9,则x+2y+3z=______.
已知2x-y-z=0,3x+4y-2z=0,则x:y:z=______.
若2x=3y=5z,且x,y,z都是正数,则2x,3y,5z从小到大依次为______.
已知2x+5y+4z=15,7x+y+3z=14,则4x+y+2z的值为______.
已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.
若4x-3y-6z=0,x+2y-7z=0(xyz≠0),则x:y:z=______.
已知|x-1|+|y-2|+|z-3|=0,则x+2y+3z=______.
已知x2+y2+z2-2x+4y-6z+14=0,则x+y+z=______.
设x,y,z 都属于R,且(x-z)²-4(x-y)(y-z)=0,求证:x,y,z成等比数列.
设X,Y,Z为实数,2X,3Y,4Z成等比数列,且1/X,1/Y,1/Z成等差数列,则X/Z+Z/X的值是
若x+y+z=30,3x+y-z=50,x,y,z都为非负实数,则M=5x+4y+2z的取值范围是______.
非零实数x,y,z成等差数列,x+1,y,z与x,y,x+z都成等比数列,则y等于