What's the sum Sn of the first n terms of this given sequence?

1, 1+2, 1+2+3, 1+2+3+4, ...
The kth term is 1+2+3+ ... +k =

(I also attached a picture of the question. Thanks!)

What's the sum Sn of the first n terms of this given sequence?1, 1+2, 1+2+3, 1+2+3+4, ... The kth term is 1+2+3+ ... +k =(I also attached a picture of the quest class=

Answer :

Medunno13

Answer: [tex]\frac{k(k+1)}{2}[/tex]

Step-by-step explanation:

This is a standard formula.

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