maths proofs
posted by daz on .
Take the numbers 4 and 7.
If we square them we get 16 and 49, which added together becomes 65.
If we add 4 and 7 together first and then square we get 121.
The difference is 56. PROVE that there is a connection between the product of 4 and 7 and 56 FOR ANY PAIR OF NUMBERS YOU SELECT.

Take the numbers a and b.
If we square them we get a² and b², which added together becomes a²+b².
If we add a and b together first and then square we get (a+b)².
The difference between (a+b)² and a²+b² is....
Expand and subtract. 
is it
a²+b²+2aba²+b²
2b²+2ab
if not please help
thanks 
or is it
a²+b²+2aba²b²
2ab 
That's correct! (the last version).

thanks so much

You're welcome!