1.29   Calculate the line integral of the function;

from the origin to the point (1, 1, 1) by means of three different routes:

1. (0, 0, 0) --> (1, 1, 0) --> (1, 1, 1)

2. (0, 0, 0) --> (0, 0, 1) --> (1, 1, 1)

3. The direct straighht line.

4. What is the line integral around the closed loop that goes out along path (a) and back along path (b)?