How to prove that this is a Quadratic Optimization Problem?

Question

Show that the following problem is a Quadratic Optimization Problem. $$ \begin{array}{ll} \max & \sum\limits_{i=1}^n \left( \mu_i(z_i + x_i) - a_i \lvert x_i \rvert - b_i x_i^2 \right) \\ \text{s.t.} & (z+x)' \sum(z+x) \le s \\ & z_i + x_i \le \gamma_i z_i^{\text{total}} & i = 1, \ldots, n \\ & -\delta_i \le x_i \le \delta_i & i = 1, \ldots, n \\ & -L \le \sum\limits_{i=1}^n p_i x_i \le L \\ & \sum\limits_{i=1}^n p_i \lvert x_i \rvert \le t \\ & z_i + x_i \ge 0 & i = 1, \ldots, n \end{array} $$