Quandaries
and Queries 

Can you explain the steps for me, that get you from (a  b)^{2} to a^{2}  2ab + b^{2} Thanks John 

Hi John, This follows from what is called "the distributive property of multiplication over addition". The property is just this
but there is another way to evaluate this expression, you can distribute the multiplication over the addition and then add. What I mean is
The distributive property is that
This distribution also is valid if the multiplication is on the right
Now let's look at your problem
I want to see the first "(a  b)" as one quantity and call it x, and I also want to see the second "(a  b)" as (a + (b)). The expression is then
The distributive property then says that this is
Now use the distributive property on the right (again seeing (a  b) as (a + (1)b).
Penny 

