Since these are terms of a geometric sequence, they have a common ratio so:
Therefore x can be equal to -7/8 or 1.
The sum of n terms in a geometric sequence is equal to
When x = -7/8, the first term would be 9/8 and the common ratio would be -3.
The sum of the first ten terms would be:
When x = 1, the first term would be 3 and the ratio would be 2.