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Mathematics 14 Online
OpenStudy (anonymous):

The coefficient of the third term in the expansion of the binomial (3x^2 + 2y^3)^4 is??

OpenStudy (anonymous):

Do you know binomial expansion?

OpenStudy (anonymous):

And pascals triangle

OpenStudy (anonymous):

No we could start by explaining how to expand a binomial.

OpenStudy (anonymous):

Hmm... Truthfully I'm not the best at this but I can try unless anyone else knows this better.

OpenStudy (anonymous):

Expanding a binomial would to be to just foil the thing

OpenStudy (anonymous):

However the binomial theorem and pascals triangle makes this much easier to do with more complex binomials.

OpenStudy (mathmath333):

since u want the third term here is a short formula \(\Large\tt \begin{align} \color{black}{=\dbinom{4}{\color{red}{3}-1}(3x^2)^{4-(\color{red}{3}-1)}(2y^3)^{\color{red}{3}-1}\hspace{.33em}\\~\\ }\end{align}\)

OpenStudy (mathmath333):

for the \(\Large r^{th}\) term of \(\Large (a+b)^n\)it is \(\Large\tt \begin{align} \color{black}{\dbinom{n}{\color{red}{r}-1}(a)^{n-(\color{red}{r}-1)}(b)^{\color{red}{r}-1} \hspace{.33em}\\~\\ }\end{align}\)

OpenStudy (mathmath333):

hope it makes sense

OpenStudy (anonymous):

Isn't the coefficient a number by itself?

OpenStudy (mathmath333):

yes coefficient is a number only, not variable like \(x\) or \(y\)

OpenStudy (mathmath333):

but here as \(3x^2\) and \(2y^3\) is a variable \(3^2\) and \(2^2\) will multiply with \(\dbinom 4 2\)

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