The values of several terms in a sequence are shown in the table.

Find the first term, f(1).

Determine the common difference between terms, and then work back from the second to the first.

The difference between the fourth and second terms is 7.

Therefore, dividing 7 by 2, gives a common difference of 3.5, between the terms in the sequence.

The first term would be found by taking the second term minus the common difference.

5 - 3.5

= 1.5

The difference between the fourth and second terms is 7.

Therefore, dividing 7 by 2, gives a common difference of 3.5, between the terms in the sequence.

The first term would be found by taking the second term minus the common difference.

5 - 3.5

= 1.5

**first term is 1.5****Ask Algebra House**