What is the sum of the series nCr . 2r?

[cgchayan]

what will be the sum of this series?
$$\Sigma$$ ⁿC_r . 2^r
where r = 0 to n

 

[l'Hôpital]

Hint:
$$\sum_{r=0}^n _nC_r \cdot 2^r = \sum_{r=0}^n _nC_r \cdot 2^r \cdot 1^{n-r}$$

 

[cgchayan]

thanx

 

[Sherard]

thanks for sharing information...