Binomial Theorem

Dear Maths Help,

Thanks for the explanation. I see what's going on now.

But what if I had to do (3+2x)^4 ?
Can I still cheat using the nCr button on my calculator or do I have to do it properly?

Click to see Tony's previous question and answer on this subject.

Maths Help suggests:

Yes, Tony, there is a short-cut method.
This second question is of the form (A + X)n.

You need to use the following Binomial Expansion:

Binomial Expansion of (A + X)^n
So in your example:
  • 'A' = 3;
  • 'X' = (2x);
  • 'n' = 4.

    Which gives

    Expansion of (3 + 2x)^4

    NB: the brackets around the 2x term help you get the correct coefficients.

    Simplified expansion of (3 + 2x)^4

    Of course, because it is 'only' to the power 4, you will immediately go and multiply it out 'properly'
    just to check we were correct, won't you..?

    Click to see Tony's previous question and answer on this subject.

    Return to contents list