a) The error is that, the initial value is n=1 NOT n=3
b) The sum is
c)The explicit formula is
The recursive formula is ,
Step-by-step explanation:
The given arithmetic series is 8 + 13 + ... + 43.
The first term is , the common difference is
The nth term is given by:
We substitute the values to get:
To find how many terms are in the sequence we solve the equation:
The summation notation is
The error the student made is in the initial value.
It should be n=1 NOT n=3
b) The sum of the arithmetic series is calculated using:
We substitute o get:
c) The explicit formula we already calculated in a), which is
The recursive formula is given as:
We substitute d=5 to get: