How do you find the sum of the first 30 terms of the sequence 4,6,8,10?

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Answer 1 · 2017-01-10T00:27:10

# S_50 = 1590 #

The terms,

# 4,6,8,10 #

form an AP with a=4 and d=2 giving the terms:

# a=4, a+d=6, a+2d=8, ... #

Then the sum of the first #n#-terms is

# S_n = n/2{2a+(n-1)d} #

So

# S_50 = 50/2{2*4 + 49*2} #
# " " = 15{8 + 98} #
# " " = 15{106} #
# " " = 1590 #