If you think of a sausage machine: something goes in, the machine works its magic, and sausages come out the other end! A function machine is a little like that, just with no sausages. We have 3 important things that happen though, just like a sausage machine.

Function machines

With a function machine, we have:

something going in (input)

something happening in the machine (operation)

something coming out (output)

Is that all?

Yes! It looks just like this.

Let's watch a video to see how it works and how it can go in reverse as well.

Remember!

A function machine uses three special terms:

input

operation

output (We don't call this the answer)

Worked Examples

Question 1

Look at this function machine.

$2$2

$+$+$1$1

?

In the case above, what is the output of the function machine?

If the input was changed to $7$7, what would the new output of the function machine be?

Question 2

Look at this function machine.

$5$5

?

$7$7

What is the operation of this function machine?

$2$2

A

$7$7

B

$+$+$5$5

C

$+$+$2$2

D

$-$−$2$2

E

$\times$×$2$2

F

$2$2

A

$7$7

B

$+$+$5$5

C

$+$+$2$2

D

$-$−$2$2

E

$\times$×$2$2

F

We can reverse the direction of a function machine.

$5$5

?

$7$7

Now $7$7 is the input and $5$5 is the output.

What is the operation of this function machine now?

$\times$×$2$2

A

$-$−$2$2

B

$5$5

C

$2$2

D

$+$+$2$2

E

$-$−$7$7

F

$\times$×$2$2

A

$-$−$2$2

B

$5$5

C

$2$2

D

$+$+$2$2

E

$-$−$7$7

F

Question 3

Look at this function machine.

?

$+$+$5$5

$12$12

In the case above, what is the input of the function machine?

If the output was changed to $11$11, what would the new input of this function machine be?