Hii !

Can You help me, for this Exercice :

Prove that for all integer $\displaystyle p \geq 3$ it exist p of integers natural different two to two $\displaystyle n_1 , n_2 , ... , n_p$ Such as :

$\displaystyle \frac{1}{n_1}+\frac{1}{n_2}+...+\frac{1}{n_p} = 1$