How do you find the sum of the arithmetic series 2 + 5 + 8 + ... + 56?
The sum of an arithmetic series is
Where n is the number of terms
a_1 is the first term and
a_n is the last tern or the nth term
but in the given problem the nth term is not given , but we can determine its term by using the formula
Where d is the common difference
By substituting to the equation
So we already have the number of terms.
Now solving for the sum of the arithmetic sequence using the formula
using the givens we have , substitute to the sum formula