Hi all,(adsbygoogle = window.adsbygoogle || []).push({});

I don't know how to prove this equality:

[tex]

\sum_{k=0}^n \left(\begin{array}{cc}n\\k \end{array}\right) = 2^n

[/tex]

I tried it many times, but never achieved the result. I used induction to do the proof, but no success.

Would somebody help please?

Thank you.

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# Proof of this one

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