Binomial Theorem Ques!
find coefficient of \[x^n\] in \[(1+x+x^2)^n\]
\(((1+x)+x^2)^n=\sum _{k=0}^n\binom{n}{k} (1+x)^{(n-k)}x^{2k}\)
\(\large ((1+x)+x^2)^n=\\\large \sum _{k=0}^n\binom{n}{k} \left ({\sum _{m=0}^{n-k}\binom{n-k}{m}x^{(m)}} \right )x^{2k}\)
first term when k=0 and m=n so \( \binom{n}{0} \binom{n}{0}x^{(n)}=x^n \)
second term when k=n/4 m=n/2 \(\binom{n}{\frac{n}{4}} \binom{\frac{4n-n}{4}}{\frac{n}{2}}x^{(n)}\)
so we would have \(\Huge (\binom{n}{\frac{n}{4}} \binom{\frac{4n-n}{4}}{\frac{n}{2}}+1) x^n\)
i dont uderstand the notation you wrote under brackets if that means thsi then i gues it it correct \[1+ \frac{ n(n-1) }{ 1!}+\frac{ n(n-1)(n-2)(n-3) }{ (2!)^2 }...............\]
yes , it mean binomial coefficient
can you explain this notation?i Dont know this
ok , could u please write what is binomial theorem ?
\[(a+b)^n=\sum_{r=0}^{n} c_{r}^{n} a ^{n-r} \times b^r\]
oh ok :P so \( \binom{n}{r}=C_r^n\)
i used different notations only
ohhk ty man life saver.
girl :P
lol
so it would be \(1+C_{\frac{n}{4}}^n +C_{\frac{n}{2}}^\frac{4n-n}{4} \)
this girl is not a ordinary girl :P
oh sry i made a typo \(1+C_{\frac{n}{4}}^n C_{\frac{n}{2}}^\frac{4n-n}{4}\)
seriously. too Over powerful.
:P
:3
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