14. The 5 th term of an arithmetic series is \(4 k\), where \(k\) is a constant.
The sum of the first 8 terms of this series is \(20 k + 16\)
- Find, in terms of \(k\), an expression for the common difference of the series.
- Show that the first term of the series is \(16 - 8 k\)
Given that the 9th term of the series is 24, find
- the value of \(k\),
- the sum of the first 20 terms.
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