For this question, shouldn’t 240 also be a valid answer??
On solving the inequality of the series, we get
(n+1)(n+3) > 58080
Based on this, 240 & 279 both satisfy the inequality
What sequence does (3,7,11, \ldots, 240) even define, though? Even if you do decide to treat it as a sum of all the elements in (3,7,11, \ldots, 239), the sum is exactly 7260, not greater than that.
It is a series, sum of numbers (3+7+11+..+n)
yes then if 239 results in exactly 7260, for 240 & 279 it will be greater than 7260
so, both 240 & 279 should be the right answers
I think you’re misunderstanding the situation here. The sequence (3,7, 11, ..., n) seems to follow the pattern 4k - 1 if we index it starting from 1. You could also define it with other more “complicated formulas”, but this is certainly the most logical form to assume given context.
Now in your case (3,7, 11, \ldots, 240), what’s the “formula” for this that you would use to retrieve the k-th term?
You’re correct that n > 239, but you’re also forgetting that n must belong to the set \{4k - 1: k \in \mathbb{Z}\}
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Understood, thanks