]The first term of an arithmetic series is 9
and the seventh term is three times the second term.
a) Find the sum of the first 32 terms.
We are told: .
In general: .
We have: .
The sum of terms is 5040:b) How many more terms must be added for the sum of the A.P. to be 5040?
This factors: .
. . and has the positive root: .
The sum of the first 32 terms is 3264.
The sum of the first 40 terms is 5040.
Therefore: . more terms must be added.