Showing $\mathbb{Q}(\sqrt{a},\sqrt{b})= \mathbb{Q}(\sqrt{a}+\sqrt{b})$
Show that if $\sqrt{a}+\sqrt{b}\neq 0$, then $\mathbb{Q}(\sqrt{a}+\sqrt{b}) = \mathbb{Q}(\sqrt{a},\sqrt{b}), \forall a,b\in\mathbb{Q}$