化简求职：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²

来源：学生作业帮编辑：搜搜考试网作业帮分类：数学作业时间：2024/06/23 03:26:27

化简求职：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²
化简求值：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²
化简求值：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²,其中x=1,y=-1,z=1

（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²
=-（2x-y+3z）(2x+y+3z)-(x+2y-3z)²
=-[(2x+3z)²-y²]-(x+2y)²+6z(x+2y)-9z²
=-4x²-12xz-9z²+y²-x²-4xy-4y²+6xz+12yz-9z²
=-5x²-3y²-18z²-6xz+12yz-4xy
再问：化简求值：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)²,其中x=1,y=-1,z=1
再答：（2x-y+3z）(-2x-y-3z)-(x+2y-3z)² =-（2x-y+3z）(2x+y+3z)-(x+2y-3z)² =-[(2x+3z)²-y²]-(x+2y)²+6z(x+2y)-9z² =-4x²-12xz-9z²+y²-x²-4xy-4y²+6xz+12yz-9z² =-5x²-3y²-18z²-6xz+12yz-4xy 当x=1,y=-1，z=1时原式=-5-3-18-6-12+4 =-40

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) x/2=y/3=z/5 x+3y-z/x-3y+z 1.（x+y-z)+(x-y+z)-(x-y-z) 2.2x-(3x-2y+3)-(5y-2) 因式分解：25x y^2 z^2 (x+y-z)-30xyz(z-x-y)^2+5x y z^3 (z-x-y) 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 x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, 证明：（y+z-2x）3+（z+x-2y）3+（x+y-2z）3=3（y+z-2x）（z+x-2y）（x+y-2z）．如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, （2x-3y+z）-3{x-2【-z+（x-y）】-（3y-5z）} (y-x)/(x+z-2y)(x+y-2z)+(z-y)(x-y)/(x+y-2z)(y+z-2x)+(x-z)(y-z (x-3y+2z)²= 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/（除以）x-y+z的值.