Chứng minh (x+y+z)^2-x^2-y^2-z^2=2(xy+yz+zx)
2) cho xyz=2016
chứng minh rằng 2016x/xy+2016x+2016 + y/yz+y+2016 + z/xz+z+1 = 1
cho ( x +y +z)( xy +yz +xz) =xyz. CHỨNg minh rằng:
x2017 + y2017 +z2017 = (x+y+z)2017
THanks for your help!!!!!~~~~~
Cho (x+y+z).(xy+yz+zx)=xyz Chứng minh: x2015+ y2015+ z2015= (x+y+z)2015
\(\dfrac{xyz-xy-yz-zx+x+y+z-1}{xyz+xy+yz-zx-x+y-z-1}\) với x = 5001;y=5002;z=5003
Cho \(\left(x+y+z\right)\left(xy+yz+zx\right)=xyz\)
Chứng minh rằng \(x^{2015}+y^{2015}+z^{2015}=\left(x+y+z\right)^{2015}\)
Cho \(x^2+y^2+z^2=xy+yz+zx\) Chứng minh rằng x=y=z
Cho x+y+z + 2 = xyz.
Chứng minh: \(x+y+z+6\ge2\left[\sqrt{xy}+\sqrt{yz}+\sqrt{zx}\right]\)
Cho các số thực x,y,z thỏa mãn xyz=2021
Chứng minh rằng \(\frac{1}{xy+x+1}+\frac{2021}{yz+2021y+2021}+\frac{2021}{zx+z+2021}=1\)
cho (x+y+z) (xy+yz+zx)=xyz .CMR:
x^2017+y^2017+z^2017= (x+y+z)^2017