Vì x-y-z = 0 => x = z + y ; y = x - z ; -z = y - x
Ta có: \(B=\left(1-\frac{z}{x}\right)\left(1-\frac{x}{y}\right)\left(1+\frac{y}{z}\right)\)
\(=\frac{x-z}{x}\cdot\frac{y-x}{y}\cdot\frac{z+y}{z}\)
\(=\frac{y}{x}\cdot\frac{-z}{y}\cdot\frac{x}{z}=-1\)