# SOLUTION: I really could use some help with this problem. (SUM 14)(-0.4i+4) i=1 I would appreciate any help that I can get.

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 Algebra: Sequences of numbers, series and how to sum them Solvers Lessons Answers archive Quiz In Depth

 Question 152219: I really could use some help with this problem. (SUM 14)(-0.4i+4) i=1 I would appreciate any help that I can get.Answer by oscargut(891)   (Show Source): You can put this solution on YOUR website!Sum (from i=1 to i=14)of (-0.4i+4) there are 2 ways of doing it 1) writing all terms Sum = S = [-0.4(1)+4]+[-0.4(2)+4]+.......[-0.4(14)+4]=14 2) using that sum(from i=0 to i=n)of (i)=i(i+1)/2 (Example sum (from i=1 to i=5) of (i) is 5(6)/2=15) then the sum S= Sum (from i=1 to i=14)of (-0.4i+4)=(using properties of a finite sum)=-0.4[sum (from i=1 to i=14) of (i)]+14(4)= -0.4[14*15/2]+56=-0.4(105)+56=-42+56=14 Answer: S=14