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C2 Binomial expansion - method help

Find the coefficient of X^3 in the expansion of

So...



To get the coefficients of X^3 do I multiply (1 * 280x^3), and (1/4x^2 * 14x)?

Then do I add the results together? I can't seem to find a clear explanation on how to do this.

Thanks
Reply 1
Avatar for TenOfThem
TenOfThem
18
You have to find all of the x^3 terms

1/4x^2 * 14x

-x*84x^2

1*280x^3

So you would be missing the middle one
Reply 2
Avatar for newskills
newskills
OP
Ah yes! Thanks. I get the answer as 199.5 which is now correct.

So when a question asks to find the coefficient of x in the expansion of two functions, do I always add the coefficients together?

Thanks.
Reply 3
Avatar for TenOfThem
TenOfThem
18
yes :smile:

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