Ответ:

  1. \((x+\sqrt{y})^2=x^2+2x\sqrt{y}+y\).
  2. \((\sqrt{x}+\sqrt{xy})^2=x+2\sqrt{x}\sqrt{xy}+xy=x+2x\sqrt{y}+xy\).
  3. \((3\sqrt{6}-2\sqrt{3})^2=54-12\sqrt{18}+12=66-36\sqrt{2}\).
  4. \((4\sqrt{5}-7\sqrt{5})^2=(-3\sqrt{5})^2=45\).