若x+y+z=a,xy+yz+zx=b,xyz=c,则xy^2+x^2y+yz^2+y^2z+xz^2+x^2z=?

已知:x+y+z=a,xy+yz+zx=b,则x^2+y^2+z^2等于多少. 若a/x^2-yz=b/y^2-zx=c/z^2-xy,求证ax+by+cz=(a+b+c)(x+y+z) 若x,y,z属于R+,且x+y+z=a,则xy+yz+zx的最值?） 实数a.b.c满足x+y+z=5,xy+yz+zx=3,求z的最大值 若x+y+z=a,xy+yz+zx=b,xyz=c,则xy^2+x^2y+yz^2+y^2z+xz^2+x^2z=? a/x*x-yz=b/y*y-zx=c/z*z-xy求证ax+by+cz=(x+y+z)*(a+b+c) 若x+y+z=6,xy+yz+zx=11,xyz=6,则x/yz+y/zx+z/xy= 若x+y+z=6,xy+yz+zx=11,xyz=6,则x/yz+y/zx+z/xy= 已知x+y+z=a ,xy+yz+zx=b ,求x2+y2+z22代表平方 xy+yz+zx=1,求x√yz+y√zx+z√xy是小于等于 若xy+yz+zx=0,则3xy+x2(y+z)+y2(z+x)+z2(x+y)等于多少 二个数学证明题1.证明：x+y 4 已知：---------- >= ------- 证明：xy(4-xy) 4+x+yx+y y+z z+x---------+ ---------- + ---------- >=2xy(4-xy) yz(4-yz) zx(4-zx)a b c2证明：若a,b,c属于R+,证明：------- + -------- + -------- >= 1b+2c c+2 a/x^2-yz=b/y^2-zx=c/z^2-xy xyz=0 求证ax+by+cz=(a+b+c)(x+y+z) 若xyz=1,求 x/(xy+x+1) +y/(yz+y+z) +z/(zx+z+1)越快越好~. 分式题:xy=x+y,yz=2(y+z),zx=3(z+x),求xyz/(xy+yz+xz)xy=x+y,yz=2(y+z),zx=3(z+x),求xyz/(xy+yz+xz) 求证不等式 xyz[yz(y+z)+zx(z+x)+xy(x+y)]>=2(xy+yz+xz)^2 几道奥数计算题1/（a-b)+1/（a+b)+2a/(a^2+b^2)+(4a^3)/(a^4+b^4)=?[(x^2+yz)/(x^2+(y+z)-yz)]+[(y^2-zx)/(y^2+(z+x)y+zx)]+[(z^2+xy)/(z^2-(x-y)z-xy]会多少写多少 乘法公式习题已知x+y+z=a,xy+yz+zx=b,求x方+y方+z方