How do you find the sum of the first 10 terms of #2+6+10+14+18+...#?

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Answer 1 · 2016-08-08T08:06:30

#S_10 = 200#

There are two formulae to find the sum of the terms of an AP.

In this case we know the following:

#a = 2" " d = 4 " " n = 10 " "S_n = n/2[2a+(n-1)d]#

#S_10 = 10/2[2(2)+(9)4]#

#S_10 = 5[4+36]#

#S_10 = 200#

The other formula requires the last term, which is this case we do not know, but if necessary, we could work out.

#S_10 = n/2(a+l)#