+55 
Please hep me I do not understand this at all. Thank you so much this means a lot!!!
+129852 First one
Not sure how to input these into your calculator..(you might have to ask your teacher).....but here is the result :
https://www.wolframalpha.com/input/?i=sum+%5B100(-4)%5E(n+-+1)%5D,+n+%3D+1+to+n+%3D+4
Second one....likewise....we have
https://www.wolframalpha.com/input/?i=sum+%5B98+-+2n%5D+,++n+%3D+1+to+n+%3D+11
