We have only been taught how to do single bracket expansions, so this is my first bracket one, so please can you tell me if Ive done anything wrong?

P.S I dont know how to use the factorial method so Im using pascal's triangle. If anyone has any helpful points on the factorial method, please tell me

Ok:

1)

Equals:

2) Multiply by first bracket:

Equals:

Note: put in brackets to make it easier to read.

3) Put in order up to

....

I got the above answer, however the book's answers got

and I cannot find the extra

that I am missing

I am guessing the method that I used is correct or not? and how would this question be done using the

and

button on my calculator?

Thankyou very much!