\(\sqrt{25}=5\\ \frac{2\sqrt{25}}{4\sqrt{10}}=\frac{2*5}{4*\sqrt{10}}=\frac{5}{2\sqrt{10}}\\ \text{Multiply the numerator and denominator by the denominator to get rid of the radical on the bottom}\\ \frac{5}{2\sqrt{10}}*\frac{2\sqrt{10}}{2\sqrt{10}}\\ \frac{10\sqrt{10}}{4*10}=\frac{\sqrt{10}}{4}\)
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