Ответ:

  1. \(\sqrt{20}+\sqrt5-\sqrt{45}=2\sqrt5+\sqrt5-3\sqrt5=0\).
  2. \(\sqrt{28}-\sqrt{63}+\sqrt{175}=2\sqrt7-3\sqrt7+5\sqrt7=4\sqrt7\).
  3. \(\sqrt{128}-\sqrt{50}+2\sqrt{18}=8\sqrt2-5\sqrt2+6\sqrt2=9\sqrt2\).
  4. \((3-2\sqrt2)^2=9-12\sqrt2+8=17-12\sqrt2\).
  5. \((6-\sqrt{11})(6+\sqrt{11})=36-11=25\).
  6. \((\sqrt{10}+\sqrt3)(\sqrt{10}-\sqrt3)=10-3=7\).