Sorry, don't know how to use latex at the moment, but:
Summation from k=0 to infinity of (k+2)2^(-k)
It says to sum the series.
I'm really unsure where to start in this problem. The only similarity I can notice is 1/(1-x) which equals the summation of x^k, but I don't think you can plug in -k's to change summations, can you?
Nvm, put it in LaTex too.