Evaluate
3\sqrt{5}\approx 6.708203932
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3\times 2\sqrt{5}-\sqrt{45}
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}.
6\sqrt{5}-\sqrt{45}
Multiply 3 and 2 to get 6.
6\sqrt{5}-3\sqrt{5}
Factor 45=3^{2}\times 5. Rewrite the square root of the product \sqrt{3^{2}\times 5} as the product of square roots \sqrt{3^{2}}\sqrt{5}. Take the square root of 3^{2}.
3\sqrt{5}
Combine 6\sqrt{5} and -3\sqrt{5} to get 3\sqrt{5}.
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