Exercise 13.5 Let $x, y \in \mathbb{R}^n$. What implications (i.e., $(a) \implies (b)$ or $(b) \implies (a)$) are valid between the following statements? If you claim an implication is true, then you need to prove is. If you are convinced a statement is false, then provide a counterexample.
(a) $(x, y) = 0$,
(b) For every $\lambda \in \mathbb{R}$ it follows that $||x|| \le ||x + \lambda y||$.