21

2.5 function transformations

Embed Size (px)

Citation preview

• When we make a new function

based on an old one, we call it a

function transformation• Four basic categories:

• Translations (shifting)

• Dilations (shrinking or stretching)

• Rotations

• Reflections

We can use function notation to build new functions:

Example 1:

The outputs for k are the same as for f except we add 3 to them

Example 2:

The outputs for k are 2 times the outputs for f

( ) ( ) 3k x f x

( ) 2 ( )k x f x

Let f(x) be defined by:

Create the new function

x 0 1 2 3 4

f(x) 8 7 9 -2 5

x

k(x)

( ) ( ) 3k x f x

x 0 1 2 3 4

f(x) 8 7 9 -2 5

x

f(x) - 7

x

f(x)+10

Use f(x) to complete the tables below:

x 0 1 2 3 4

g(x) 12 9 -4 0 -1

x

g(x) – 3

Use g(x) to complete the table below:

Let f(x) be

defined by:

Graph the

new function:

( ) ( ) 2k x f x

Let f(x) be

defined by:

Graph the new

function:

( ) ( ) 1k x f x

Use the same f(x)

from the example:

Draw a graph for

the new function

Vertical shifts added/subtracted

something to the output values.

Horizontal shifts will add/subtract

something to the input values.

Example: h(x) = f(x + 1)

is a horizontal shift.

When the input is changed, we need to “undo” that change to see what happens to the graph/table.

So, f(x + 1) means we subtract 1from the x values.

And, f(x – 1) means we add 1 to thex values.

Output values stay the same!

Add/subtract (do the opposite!) to

change the input values.

Example:

Make a table for the new function

x 0 1 2 3 4

f(x) 8 7 9 -2 5

( ) ( 1)k x f x

x

k(x)

Make a table for the new function

x 0 1 2 3 4

f(x) 8 7 9 -2 5

x

g(x)

Remember we “undo” any change

to the input, so:

(x - #) means add shift right

(x + #) means subtract shift left

Here is f(x):

Sketch:

Here is f(x).

Sketch:

Dilations occur when a function is

multiplied by a number.

Vertical dilations – outputs multiplied

◦2f(x)

Horizontal dilations – inputs

multiplied

◦ f(2x) (We will only do vertical

stretches/shrinks this year.)

Make a table for the new function

x 0 1 2 3 4

f(x) 8 7 9 -2 5

x

g(x)

Make a table for the new function

x 0 1 2 3 4

f(x) 8 7 9 -2 5

x

h(x)

Here is f(x):

Sketch:

Here is f(x):

Sketch: