Question

Answer 1

\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)

= \(\sqrt{2^2.5}\) - \(\sqrt{3^2.5}\) + \(3\sqrt{2.3^2}\) + \(\sqrt{2.6^2}\)

= \(2\sqrt{5}-3\sqrt{5}+9\sqrt{2}+6\sqrt{2}\)

= \(\sqrt{5}\left(2-3\right)\) + \(\sqrt{2}\left(9+6\right)\)

= -\(\sqrt{5}+15\sqrt{2}\)

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Answer 2

\(\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}\)

\(=2\sqrt{5}-3\sqrt{5}+9\sqrt{2}+6\sqrt{2}\)

\(=15\sqrt{2}-\sqrt{5}\)