## shortcut for exponential problem

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
latinlioness08
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Joined: Mon Apr 11, 2011 1:48 am
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### shortcut for exponential problem

The coefficient in front of the x^5 term in (x+2)^7 is:
a. 21
b. 7
c. 42
d. 84

I know the answer is d. However, to aquire this answer I had to literally FOIL the entire thing. I took it to (x^4+ 8x^3+24x^2+32x+16)(x^3+6x^2+12x+8) before i knew how to tell what the answer was. Is there some shortcut to know what the coefficient in front of the x^n term is in a basic expression like this?

stapel_eliz
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Is there some shortcut to know what the coefficient in front of the x^n term is in a basic expression like this?
Yes, there is a shortcut. It's called "the Binomial Theorem".

latinlioness08
Posts: 2
Joined: Mon Apr 11, 2011 1:48 am
Contact:

### Re: shortcut for exponential problem

Got it:) Thanks!

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