Question 7
(CZS 1) Find all real solutions of the system of equations
$$\begin{aligned}x_1+x_2+\cdots+x_n&=a,\\x_1^2+x_2^2+\cdots+x_n^2&=a^2,\\&\ \vdots\\x_1^n+x_2^n+\cdots+x_n^n&=a^n.\end{aligned}$$
$$\begin{aligned}x_1+x_2+\cdots+x_n&=a,\\x_1^2+x_2^2+\cdots+x_n^2&=a^2,\\&\ \vdots\\x_1^n+x_2^n+\cdots+x_n^n&=a^n.\end{aligned}$$