Dani su realni brojevi x0>x1>x2>⋯>xnx_0 > x_1 > x_2 > \cdots > x_nx0>x1>x2>⋯>xn. Dokaži da je x0−xn+1x0−x1+1x1−x2+⋯+1xn−1−xn≥2n.x_0 - x_n + \frac{1}{x_0 - x_1} + \frac{1}{x_1 - x_2} + \cdots + \frac{1}{x_{n-1} - x_n} \geq 2n.x0−xn+x0−x11+x1−x21+⋯+xn−1−xn1≥2n.
Kada vrijedi jednakost?