Evaluate each of the following sums.

1. $2m+1+3m−$$1+4m−3+\dots+$$25m−45$ 

   Hint (a):

   This is an arithmetic series with a common difference of $m − 2$.

2. $−4a+2a^3−$$a^5+\dots$ 

   Hint (b):

   This is a geometric series with a common ratio of $−0.5a^{2}$.