Question

tìm M bt: xyz = 2; x+y+z=0

M= (x+y).(y+z).(x+z)

Answer 1

Ta có: x+y+z=0

\(\Rightarrow\left\{{}\begin{matrix}x+y=-z\\y+z=-x\\x+z=-y\end{matrix}\right.\)

M=(x+y)(y+z)(x+z)=(-z).(-x).-(y)=-x.y.z=-2

Answer 2

ta có x+y+z=0

\(\Rightarrow x+y=-z\\ y+z=-x\\ x+z=-y\)

M=(x+y).(y+z).(x+z)=(-z).(-x).(-y)=-(x+y+z)

mà x+y+z=2 \(\Rightarrow-\left(x+y+z\right)=-2\)