Evaluate
8\sqrt{5}\approx 17.88854382
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4\sqrt{5}+2\times 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}.
4\sqrt{5}+4\sqrt{5}
Multiply 2 and 2 to get 4.
8\sqrt{5}
Combine 4\sqrt{5} and 4\sqrt{5} to get 8\sqrt{5}.
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