Ответ:

  1. \(3\sqrt3-4\cdot3\sqrt3+5\cdot4\sqrt3=(3-12+20)\sqrt3=11\sqrt3.\)

  2. \((4\sqrt{10}-2\sqrt{10})\sqrt{10}=2\sqrt{10}\cdot\sqrt{10}=20.\)

  3. \((2\sqrt3-4)^2=12-16\sqrt3+16=28-16\sqrt3.\)

  4. \((4\sqrt5-3\sqrt3)(4\sqrt5+3\sqrt3)=(4\sqrt5)^2-(3\sqrt3)^2=80-27=53.\)

Ответ: 1) \(11\sqrt3\); 2) 20; 3) \(28-16\sqrt3\); 4) 53.