# Triangle Inequality/Real Numbers/Proof 2

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## Theorem

Let $x, y \in \R$ be real numbers.

Let $\size x$ denote the absolute value of $x$.

Then:

$\size {x + y} \le \size x + \size y$

## Proof

This can be seen to be a special case of Minkowski's Inequality, with $n = 1$.

$\blacksquare$