Here is a depiction of
The sides of the outer square are . The area of the outer square represents
We can see this is made up of the red
square and the two yellow 5
rectangles and the blue
square.
We can rearrange these shapes to show this more clearly. gives
We can generalise this. When we expand brackets that have the form where c is a constant, we get
Going back to our example, when the constant is 5, we get
You should be able to look at similar brackets that are squared and be able to quickly see what the terms expand to.
For example
You may even get to the stage where you can look at some squared bracketed term like and see straight away that this is the same as