How do you use the properties of summation to evaluate the sum of #Sigma 2i# from i=1 to 20?
1 Answer
Jan 5, 2017
Explanation:
Use the standard summation formula
# sum_(r=1)^n r = 1/2n(n+1) #
# sum_(i=1)^20 (2i) = 2sum_(i=1)^20 i #
# " " = 2*1/2(20)(21) #
# " " = 420 #
