[tex]a = 4\sqrt{15}+4\sqrt{35}+4\sqrt{21}+30\\ \\ \text{Fie }b = \sqrt{4\sqrt{15}+4\sqrt{35}+4\sqrt{21}+30},\quad b\in \mathbb{R}\\ \\b^2 =\left(\sqrt{4\sqrt{15}+4\sqrt{35}+4\sqrt{21}+30}\right)^2\\ =4\sqrt{15}+4\sqrt{35}+4\sqrt{21}+30\\ = a\\ \\ \Rightarrow \boxed{a = b^2}[/tex]
