[tex]\it \dfrac{x}{2\sqrt5} = \dfrac{\sqrt{45}}{x} \Rightarrow x\cdot x = 2\sqrt5\cdot\sqrt{45} \Rightarrow x^2 = 2\sqrt{225} \Rightarrow x^2 = 2\cdot15 \Rightarrow
\\\;\\ \\\;\\
\Rightarrow x^2 = 30 \Rightarrow \sqrt{x^2} = \sqrt{30} \Rightarrow |x| =\sqrt{30} \Rightarrow x = \pm \sqrt{30}[/tex]
