计算:(3x+2y-z)(-3x+2y-z)
运用乘法公式计算:(x+2y-3z)(x-2y+3z)
计算:3x-2y- [-4x+(z+3y)]
证明:(y+z-2x)3+(z+x-2y)3+(x+y-2z)3=3(y+z-2x)(z+x-2y)(x+y-2z).
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
(2x-3y+z)-3{x-2【-z+(x-y)】-(3y-5z)}
计算(x+2y-3z)的平方+(x-2y+3z)(x+2y-3z)
(x+2y+3z)-(3x+2y-z)+(2x-3y+4z) 用直式计算
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.
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,