Apply the binomial expansion to : (1+x)^n and show that the coefiicient of x^n in the expansion of (1+x)^2n is:(adsbygoogle = window.adsbygoogle || []).push({});

(nC0)^2 +(nC1)^2 +...+(nCn)^2

hint: (nCm)=(nC(n-m))

my approach:

(1+x)^n = x^n + nx^(n-1) + (nC2)x^(n-2) +...+ 1

(1+x)^2n = x^(2n) + nx^(2n-1) +...+ x^n

i dont know what to do next. it looks easy but i cant figure it out.

can someone help me please?.

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# Binomial expansion

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