Evaluate
4\sqrt{5}\approx 8.94427191
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4\sqrt{5}-\sqrt{20}+2\sqrt{5}
Factor 80=4^{2}\times 5. Rewrite the square root of the product \sqrt{4^{2}\times 5} as the product of square roots \sqrt{4^{2}}\sqrt{5}. Take the square root of 4^{2}.
4\sqrt{5}-2\sqrt{5}+2\sqrt{5}
Factor 20=2^{2}\times 5. Rewrite the square root of the product \sqrt{2^{2}\times 5} as the product of square roots \sqrt{2^{2}}\sqrt{5}. Take the square root of 2^{2}.
2\sqrt{5}+2\sqrt{5}
Combine 4\sqrt{5} and -2\sqrt{5} to get 2\sqrt{5}.
4\sqrt{5}
Combine 2\sqrt{5} and 2\sqrt{5} to get 4\sqrt{5}.
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