填空:(x-y-z)(_________)=x^2-(y+z)^2
x,y,z为正实数 x/(2x+y+z)+y/(x+2y+z)+z/(x+y+2z)
证明:(y+z-2x)3+(z+x-2y)3+(x+y-2z)3=3(y+z-2x)(z+x-2y)(x+y-2z).
x分之y+z=y分之z+x=z分之x+y(x+y+z不等于0),求x+y+z分之x+y-z
已知x+y-7z=0 x-2y+5z=0(xyz不等于0),求x+2y-z/y-2x+12z
已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/(除以)x-y+z的值.
已知x::y:z=3:4:5,(1)求x+y分之z的值;(2)若x+y+z=6,求x,y,z.
①(x+y+z)(-x+y+z)(x-y+z)(x+y-z)
已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z都不为0,求(3x*x+y*y+4z*z)/(5x*x+y*
x.y.z.m都是有理数,并且x+y+2z=m,x+2y+3z=m,那么y与z( )
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,
(x+y+z)*(-x+y+z)*(x-y+z)*(x+y-z)=
已知x/2=y/3=z/4,求下列各式 (1)(x+y+z)/x (2)(x-y+2x/(x-y-2z)