Explain why an infinite geometric series will not have a sum if .
The sum for infinite geometric series is .
If then the sum of the series increases without limit.
Therefore, the corresponding sequence will be divergent, and the sum of the series cannot be calculated.
\Consider the geometric series is .
The common ration is .
The sum of the series is .
.
Consider the geometric series .
The common ratio is .
The sum of the series is .
.
Therefore, the value is not the correct value for sum. \ \
Therefore, the formula for the sum of an infinite geometric series does not work when .
The formula for the sum of an infinite geometric series does not work when . \ \