311. 1) \(2^3+5\sqrt{16}\); 2) \(3\sqrt{121}-2\sqrt{144}\); 3) \(2\sqrt{3\cdot27}-6\sqrt{2\cdot18}\); 4) \(\sqrt{2^2+3\cdot7}\); 5) \(\sqrt{3^2+4^2}\); 6) \(\sqrt{17^2-15^2}\).

1. \(2^3+5\sqrt{16}=8+5\cdot4=28\).
2. \(3\sqrt{121}-2\sqrt{144}=3\cdot11-2\cdot12=33-24=9\).
3. \(2\sqrt{3\cdot27}-6\sqrt{2\cdot18}=2\sqrt{81}-6\sqrt{36}=2\cdot9-6\cdot6=18-36=-18\).
4. \(\sqrt{2^2+3\cdot7}=\sqrt{4+21}=\sqrt{25}=5\).
5. \(\sqrt{3^2+4^2}=\sqrt{9+16}=\sqrt{25}=5\).
6. \(\sqrt{17^2-15^2}=\sqrt{289-225}=\sqrt{64}=8\).

Ответ: 1) 28; 2) 9; 3) −18; 4) 5; 5) 5; 6) 8.