Ответ:

  1. \(\sqrt{a-b}=\sqrt{0.93-0.57}=\sqrt{0.36}=0.6\).
  2. \(\sqrt{a-b}=\sqrt{\frac34-\left(-\frac1{18}\right)}=\sqrt{\frac{27}{36}+\frac{2}{36}}=\sqrt{\frac{29}{36}}=\frac{\sqrt{29}}6\).

Ответ: 1) 0,6; 2) \(\frac{\sqrt{29}}6\).