(i) Suppose x10 occurs in the (r + 1)th term in the given expression.
Then, we have:
Here,
(ii) Suppose x7 occurs at the (r + 1) th term in the given expression.
Then, we have:
(iii) Suppose x−15 occurs at the (r + 1)th term in the given expression.
Then, we have:
(iv) Suppose x9 occurs at the (r + 1)th term in the above expression.
Then, we have:
(v)
Suppose xm occurs at the (r + 1)th term in the given expression.
Then, we have:
(vi) Suppose x occurs at the (r + 1)th term in the given expression.
Then, we have:
(vii)
Suppose a5 b7 occurs at the (r + 1)th term in the given expression.
Then, we have:
(viii) Suppose x occurs at the (r + 1)th term in the given expression.
Then, we have: