Why is this answer wrong? I used the number of integers in an interval and sum of integers interval formula but not correct

also there is no solution to this at all.

We know that the sum of an arithmetic sequence is as follows:

S_n = \frac n2 (2a_1 + (n-1)d)

and so plugging numbers in should leave you with S_n = \frac{600}{2}(2\cdot 3 + (600-1)\cdot 2) = 361200

Idk what you mean with “number of integers in intervals and sum of integers…” thing, but a solution to this question could look like what i have written above.

but this wasn’t covered in greg videos

:thinking:, what was covered then? I can’t give you specific help if you don’t provide context, right?

this was series 1 video and greg never covered this formula anywhere in this video. it is really disheartening throwing in questions like this and making a topic so difficult

You can use the approaches described in “number/sum of integers in an interval”. Share your steps.

Hi Greg
I used the number of integers in the interval to which was 599-3+1 and then the sum of integers in the interval which is 599+3 and then multiplied both to get divided by 2.
But the answer was way off

How? In particular, how’s the 600th term of the sequence “599”?