The third term of an arithmetic sequence is 14, and the ninth term is -1. How do you find the first four terms of the sequence?
You can write an equation (or formula) for each term in an AP.
"The third term is 14" can be written with the formula as:
"The ninth term is -1 " can be written as:
Now there are two equations with two unknowns.
Solve them simultaneously (as a system).
This sequence is given by
Each term is 2.5 less than the previous term: