binomials (1 Viewer)

fannymasta · Jun 10, 2009

someone help me, i think its easy but i needa know the concept

(1+px)^n = 1 + 15x + 90x^2 + ... find the values of p and n

ianc · Jun 11, 2009

Hi there

hopefully this makes sense, i didn't bother working out the answer, but here's the method

$\textup{the binomial theorem tells us:} \newline(x+y)^n=\sum_{k=0}^{n}\binom{n}{k}x^{n-k}y^{k} \newline\textup{so just adapt that to fit this question:} \newline(1+px)^n=\sum_{k=0}^{n}\binom{n}{k}p^{k}x^{k} \newline\newline\textup{they've given us the first 3 coefficients} \newline\newline\binom{n}{0}p^{0}=1\textup{ (trivial)} \newline\newline\binom{n}{1}p=15 \newline\newline\binom{n}{2}p^2=90 \newline\textup{so now you have 2 equations with 2 unknowns which should be pretty easy to solve}$

hope this helps

Pwnage101 · Jun 11, 2009

n=5, p=3

binomials (1 Viewer)

fannymasta

New Member

ianc

physics is phun!

Pwnage101

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