Question 11
Find the positive difference between the sum of all possible integers $x$ and the sum of all possible integers $y$ satisfying $x^y=81$.
**Convention used by the source solution and by this exercise:** List every integer solution pair $(x,y)$ once, and add its first and second coordinates separately. Thus a repeated coordinate is counted once for each pair in which it occurs.
**Convention used by the source solution and by this exercise:** List every integer solution pair $(x,y)$ once, and add its first and second coordinates separately. Thus a repeated coordinate is counted once for each pair in which it occurs.