IXL - Write linear and exponential functions from tables (Algebra 1 practice)

Look at this table:

x	y
0	4
1	12
2	36
3	108
4	324

Write a linear function

(

)

or an exponential function

(

)

that models the data.

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Learn with an example

question

Look at this table:

x	y
3	– 8
4	– 14
5	– 20
6	– 26
7	– 32

Write a linear function

(

)

or an exponential function

(

)

that models the data.

key idea

You can determine if a function is linear or exponential by looking at the pattern of

-values.

solution

Since the

-values

in the table are consecutive, you can compare successive

-values

to determine which type of function the table describes.

You can test whether a function is linear by finding the differences between successive

-values.

If the differences are all equal, the function is linear.

Find the differences in the table.

x	y
3	– 8	– 6
4	– 14	– 6
5	– 20	– 6
6	– 26	– 6
7	– 32

Since the differences are all

–

the function is linear

(

When the differences are the same, the slope

is equal to the common difference,

–

Now, plug in one of the points from the table and solve for

For example, use

(

–

)

–

Plug in

(

–

)

–

(

)

Plug in

(

–

)

–

Multiply

–

Multiply

Add 18 to both sides

Since

–

and

the function is

–

Looking for more? Try this:

$Confetti$

Excellent!

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Teacher tools

Work it out

Not feeling ready yet? These can help:

AA.3Identify linear and exponential functions from tables

L.7Slope-intercept form: write an equation from a table

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