you are right. Shortly after I asked this, I realized it. In fact, Tadd's nth "term" has 1+3(n-1)=3n-2 numbers; when coming to 37, it's equivalent to 36+36+37=109, just wondering why didn't he directly use 1+3(n-1).
Solution- 1, 2 & 3, 3&4&5,...= the sequence 1+4+7+10...(3n-2), which means n/2(3n-1), by arithmetic series formula, so n could be 37 since it can't be 40, and the 37th term is 2035. The 37th turn means the 109th number, so substituting 109 to n/2(3n-1), we get 5995 as the 2035 term. But we want the 2019th term, so 5995-16= 5979, or C.
Please let amc 10a problem #25 come out now.
Not get why he got 36+36+37，shouldn't it be 35+36+37?
you are right. Shortly after I asked this, I realized it. In fact, Tadd's nth "term" has 1+3(n-1)=3n-2 numbers; when coming to 37, it's equivalent to 36+36+37=109, just wondering why didn't he directly use 1+3(n-1).
@@xz1891 Good idea too! Both methods work out though...Guess that's the art
Solution- 1, 2 & 3, 3&4&5,...= the sequence 1+4+7+10...(3n-2), which means n/2(3n-1), by arithmetic series formula, so n could be 37 since it can't be 40, and the 37th term is 2035. The 37th turn means the 109th number, so substituting 109 to n/2(3n-1), we get 5995 as the 2035 term. But we want the 2019th term, so 5995-16= 5979, or C.
he's really funny
Thanks!
you are so funny!!
he always writes a(b) for axb. also realise that AoPS has 55.5K subscribers LOL
Lol i jhust plugged in
hullo
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Seriously, he can teach with only his eyebrow. Don't believe me? Just mute the video and watch his eyebrow moving.