Ответ:

  1. При \(a=0.93\), \(b=0.57\):
    \(\sqrt{a-b}=\sqrt{0.93-0.57}=\sqrt{0.36}=0.6\).
  2. При \(a=\frac{3}{4}\), \(b=-\frac{1}{18}\):
    \(\sqrt{a-b}=\sqrt{\frac{3}{4}-\left(-\frac{1}{18}\right)}=\sqrt{\frac{3}{4}+\frac{1}{18}}=\sqrt{\frac{29}{36}}=\frac{\sqrt{29}}{6}\).

Ответ: 0,6; \(\frac{\sqrt{29}}{6}\).