Thread: Expanding with binomial theorem

Hi, I was working through some exercises and came to this:



I got an answer which starts out as:

....

etc. etc.

but the textbook answer begins:

.....

note the missing from the " " part.

This seems kooky to me, am I wrong or is the book wrong? And if I'm wrong, what did I do wrong?

You are correct. The book probably just has a typo.

Thanks for that, I was hoping it was a typo.

But I have a related question. I've continued in this exercise set and have another question about how to handle negatives, for example in the problem:



The first time I expanded this, I got .....etc.

but when I went to do the next step, I noticed that everything came out positive because of the thing.

so I rewrote it as .......etc.

This gives the right answer, but it looks messy, and I'm not happy with it because I just pulled it out of my ear, so to speak.

I guess my question is, Am I doing this correctly or should I go back and do some rereading?