Evaluate
21\sqrt{5}\approx 46.957427527
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7\times 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}.
21\sqrt{5}
Multiply 7 and 3 to get 21.
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