\left ( \sum_{i=1}^n |x_i + y_i|^p \right )^{\frac{1}{p}} \leq \left (\sum_{i=1}^n|x_i|^p \right )^{\frac{1}{p}} \left (\sum_{i=1}^n|y_i|^p \right )^{\frac{1}{p}}