Ответ:

  1. При a = 58, c = 6: √(a + c) = √(58 + 6) = √64 = 8.
  2. При a = 54, c = −18: √(a + c) = √(54 − 18) = √36 = 6.
  3. При a = 1/4, c = 4/9: √(a + c) = √(1/4 + 4/9) = √(9/36 + 16/36) = √(25/36) = 5/6.

Ответ: 8; 6; 5/6.