# How do you find the first term of the arithmetic sequence given Sn = 781, d = 3, n = 22?

##### 1 Answer

Jul 5, 2015

The first term is

#### Explanation:

In this sequence we know the sum of 22 terms, the difference and we have to calculate the first term. We will use the formula for the sum of n terms:

In this formula we have all data except

When we substitute (2) to (1) we get:

Now we can substitute given data and calculate