Find the sum of the first 21 terms of the arithmetic sequence 5, -2, -9.

-1365

Step-by-step explanation:

The difference is -7, so you apply that to each number to get your answer.

Linear

Step-by-step explanation:

If you graph this, you start at 1500 on the y-axis. Every time the x-axis increases by 1, the y-axis increases by 200. This forms a straight line, making it exponential since it increases by a constat amount.