What is the sum of the first n terms of this series?

4 + 6 + 8 + 10 + 12 + ⋯

Question

What is the sum of the first n terms of this series?

4 + 6 + 8 + 10 + 12 + ⋯

anonymous · Answer

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alekos · Answer

its asking for the first n terms so your looking for a sum from 1 to n

some.random.cool.kid · Answer

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solomonzelman · Answer

The sigma notation isn't hard.

You are summing from $i=1$ (from 4) till $i=n$ (some nth term which we don't know, but don't need for the sigma)

Your pattern here is +2 every time, and you start from 4
Hint: (Think of a line that has a slope 2, and goes through the point (1,4) )

solomonzelman · Answer

(I don't want to give it away, but do want to help.... apologize if it is not enough.

zzr0ck3r · Answer

$\sum_{k=1}^n(2k+2)=2\sum_{k=1}^nk+\sum_{k=1}^n2=2\dfrac{n(n+1)}{2}+2n=n^2+3n$

Let me know if you have any questions.