10' 1.2 sqrt(5)-sqrt(20) 11. 5 sqrt(6) cdot 5 sqrt(3) 111. 7 sqrt(3) div 5 sqrt(42) IV. sqrt(0,9)+sqrt(1,6) yubarida vecilen islemlerden hangilerinin Sonucu rosyonel sayidir?

Let's go through each expression step by step:<br /><br />1. \(2\sqrt{5} - \sqrt{2}0\)<br /><br /> This expression seems to have a typo. Assuming it should be \(2\sqrt{5} - \sqrt{20}\):<br /><br /> \[<br /> 2\sqrt{5} - \sqrt{20} = 2\sqrt{5} - \sqrt{4 \cdot 5} = 2\sqrt{5} - 2\sqrt{5} = 0<br /> \]<br /><br />2. \(5\sqrt{6} \cdot 5\sqrt{3}\)<br /><br /> \[<br /> 5\sqrt{6} \cdot 5\sqrt{3} = 5 \cdot 5 \cdot \sqrt{6 \cdot 3} = 25\sqrt{18} = 25 \cdot 3\sqrt{2} = 75\sqrt{2}<br /> \]<br /><br />3. \(7\sqrt{3} \div 5\sqrt{4}\)<br /><br /> \[<br /> 7\sqrt{3} \div 5\sqrt{4} = 7\sqrt{3} \div 5 \cdot 2 = \frac{7\sqrt{3}}{10}<br /> \]<br /><br />4. \(\sqrt{0.9} + \sqrt{4.6}\)<br /><br /> \[<br /> \sqrt{0.9} + \sqrt{4.6} \approx 0.9487 + 2.1452 \approx 3.0939<br /> \]<br /><br />So, the answers are:<br /><br />1. \(0\)<br />2. \(75\sqrt{2}\)<br />3. \(\frac{7\sqrt{3}}{10}\)<br />4. \(\approx 3.0939\)