Question

find the sum of n terms of the series 4 minus 1 upon 1n + 4 minus 2 upon 10 + 4 minus 3 upon 10 + 4 minus 4 Upon A

Answer 1

this is the summation of 4-r/n from r = 1 to r=n.
as we can see 4 is being added n times
hence the sum will have a term of 4n.
now we'll take -1/n common from those terms which will leave us to the famous sum of natural numbers which is n(n+1)
hence our sum will be :
4n -1/n x n(n+1)
solve and get 3n-1

Answer 2

hope this helps........