Question

What is the fourth term in the expansion of (x – 4)^6?

–1280x^3

–256x^4

256x^4

1280x^3

Answer 1

Use Binomial theorem.

Answer 2

We want to do this without having to work the whole thing out.
It's easy to memorize that:
\[(a+b)^6=a^6+...a^5b+...a^4b^2+...a^3b^3+...etc\]because of the nice pattern of de/increasing powers of a/b.

So... the 4th term is somethin like (unknown number)*x³(-4)³.
This means:
1. answer has x³ in it.
2. answer has a minus sign.

That leaves only one option...

Answer 3

@lornbeach: are you still there? ;)

Answer 4

haha im still confused

Answer 5

What is unclear?

Answer 6

just kidding i got it, thanks(: hahah

Answer 7

You got me there!