已知A=-xy+yz+xz,B=-2xy+yz-xz 求下列式子的代数和 (1) A+B (2) 3A-2B
已知X+Y+Z=a,XY+YZ+XZ=b,求X*X+Y*Y+Z*Z的值
已知xy/(x+y)=a,xz/(x+z)=b,yz/(y+z)=c,且a.b.c不等于0,求x的值
已知:xy/(x+y)=a,xz/(x+z)=b,yz/(y+z)=c,且abc不等于0,求证:x=2abc/(bc+a
已知:xy/(x+y)=a,xz/(x+z)=b,yz/(y+z)=c,且abc不等于0,求证:x=2abc/(bc+a
已知X-Y=A,Y-Z=B,求X方+Y方+Z方-XY-YZ-XZ的值
若实数xyz满足(x-2y+z)^2+4(x-y)(y-z)=0 A xy-yz=0 B xy+yz=0 C xy-xz
一元二次方程的应用 已知xy=xz+3,yz=xy+xz-7(x,y,z均为正整数),求2(xy+yz+xz)的值.
若x/2=1/y=z/3,且xy+xz+yz=99,求4x^2-2xz+3yz-9y^2的值.
yz/(bz+cy)=xz/(cx+az)=xy/(ay+bx)=(x^2+y^2+z^2)/(a^2+b^2+c^2)
如果xy=a,xz=b,yz=c,abc≠0,那么x^2+y^2+z^2=______
已知a,b,c,x,y,z,是互不相等的非零实数,且 yz/(bz+cy)=xz/(cx+az)=xy/(ay+bx)=
已知x-y=a,y-z=8,求代数式x^2+y^2+z^2-xy-yz-xz的最小值