Binomial Theorem Question (1 Viewer)

fettywap1738 · Mar 10, 2019

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Can someone please help me with this question. Its from Maths in Focus Test Yourself 10.

fan96 · Mar 10, 2019

Firstly,

$(2-x)^n = \sum_{k=0}^n \binom{n}{k} 2^{n-k} (-x)^k$

Set $k = 2, 3$ , giving the coefficients of $x^2$ and $x^3$ :

$\binom{n}{2} 2^{n-2} (-1)^2$

and

$\binom{n}{3} 2^{n-3} (-1)^3$

Now all you need to do is to solve

$\binom{n}{2} 2^{n-2} (-1)^2 = - \left(\binom{n}{3} 2^{n-3} (-1)^3\right)$

Binomial Theorem Question (1 Viewer)

fettywap1738

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fan96

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