[Eranga]

Initially x = 5.0

Code:

double x = 5.0;

Call the power() with x = 5.0 and n = 4. Those parameters are moving on the loop as follows.

Code:

on if clause - still n > 1(n = 4) so,
       return 5.0 * power( 5.0, 3)

on if clause - still n > 1(n = 3) so,
        5.0 * return 5.0 * power( 5.0, 2)

on if clause - still n > 1(n = 3) so,
        5.0 * 5.0 * return 5.0 * power( 5.0, 1) 

skip else-if clause - n is not a negative

on else clause
      5.0 * 5.0 * 5.0 * return 5.0

So the answer is 625.0 for the first println(). Hope it's help