What is the sum of the arithmetic series 6 + 12 + 18 + ... + 60?

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Answer 1 · 2016-01-22T01:09:47

The common difference #d=12-6=6#

Now, determine what term is 60?

#a_n=a_1+(n-1)d#

#60=6+(n-1)(6)#

#n=10#

Now that we know 60 is the 10th term , use the sum formula ...

sum #=(a_1+a_n)/2xxn#

sum #=(6+60)/2xx10=330#

hope that helped