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Given the expression \\((\\var{a}+\\var{b}x)^{\\var{n}}\\)

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By using the binomial series expansion, calculate the coefficient of \\(x^{\\var{k}}\\)  [[0]]

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The binomial series expansion for an expression of the form \\((a+bx)^n\\) where \\(n\\) is a Natural number is given by:

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\\((a+bx)^n=\\tbinom{n}{0}(a)^n(bx)^{0}+\\tbinom{n}{1}(a)^{n-1}(bx)^{1}+\\tbinom{n}{2}(a)^{n-2}(bx)^{2}+...\\tbinom{n}{k}(a)^{n-k}(bx)^{k}+...\\tbinom{n}{n}(a)^{0}(bx)^{n}\\)

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In this example  \\(n=\\var{n}\\),  \\(k=\\var{k}\\),  \\(a=\\var{a}\\)  and  \\(b=\\var{b}\\).

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So the coefficient of \\(x^{\\var{k}}\\) is given by \\(\\tbinom{\\var{n}}{\\var{k}}*\\var{a}^{\\var{n}-\\var{k}}*\\var{b}^{\\var{k}}=\\var{c}\\).

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