Begin to Use Concepts of Algebra

We have learned about the the language of maths in a previous activity.

We used words such as variables, terms, expressions and equations.

In this activity, we will begin to use concepts to help us with algebra for the future.

For this we need to know the inverse operations:

+ is the inverse of -

x is the inverse of ÷

and vice versa

Let's try an example:

Donny is thinking of a number.
He says "If I double my number and add 5, the answer is 15"
What number did Donny start with?

Answer

To find this number, we start with the output, which is 15.

In order to get back to the start, we do the inverse to 15, as we do with a function machine.

So, we start with 15 and do 15 - 5 = 10.

Then we divide by 2: 10 ÷ 2 = 5

Donny started with 5.

We can check by doubling 5 = 10
Adding 5 = 15 

It's correct!

Let's try some questions now.