binomial expansion - 2 brackets!

find the co-efficient of x in the expansion of

(1-2x)^4 (2+x)^9

where do i start?? i can do binomial expansion with one bracket (nCr etc.) but i dont know how to go about doing this. can anyone give me hint please?

Reply 1

02k7

should have probably mentioned its C2 as level aqa =]

Reply 2

Kyalimers

Binomial expansion of both brackets seperately. Then multiply???

Reply 3

Glutamic Acid

There's no need to expand it all, just expand each bracket as far as the x term. Can you see why this is all you need to do? And do you now see how to find the coefficient of x for the whole thing?