[tex]a)\ \ \sqrt{2}\cdot\sqrt{3}=\sqrt{2\cdot3}=\sqrt{6}\\\\b)\ \ \sqrt{7}\cdot\sqrt{5}=\sqrt{7\cdot5}=\sqrt{35}\\\\e)\ \ \sqrt{3}\cdot\sqrt{5}\cdot\sqrt{15}=\sqrt{3\cdot5\cdot15}=\sqrt{15\cdot15}=\sqrt{15^2}=15\\\\f)\ \ \sqrt{2}\cdot\sqrt{8}\cdot\sqrt{10}=\sqrt{2\cdot8\cdot10}=\sqrt{16\cdot10}=\sqrt{16}\cdot\sqrt{10}=4\sqrt{10}[/tex]
[tex]Skorzystamy\ \ ze\ \ wzor\'ow\\\\\sqrt{a}\cdot\sqrt{b}=\sqrt{a\cdot b}\ \ \ \ dla\ \ a,b\geq 0\\\\\sqrt{a^2}=a\ \ \ \ dla\ \ a\geq 0x^{2}[/tex]
