### Home > A2C > Chapter 2 > Lesson 2.2.2 > Problem 2-138

2-138.

Find a rule for each sequence below. Then describe its graph. 2-138 HW eTool (Desmos). Homework Help ✎

*n**t(n)*3

8

5

2

7

−4

*n**t(n)*1

40

2

32

3

25.6

First, decide if the given sequence is arithmetic or geometric.

Common difference =

So, *t*(*n*) = −3*n* + *b*.

Find the value of *b* at (3, 8).

Write the equation once you know *b*. Then describe the graph.

*t*(*n*) = −3*n* + 17

The graph is a straight line with the *y*-intercept at (0, 17) and a slope of −3.

The multiplier is less than 1.

You will need to find *t*(0) to write the equation.

This graph is not linear.

Use the eTool below to view the graphs.

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