Given the sequence 7, 11, 15, 19,… find the 100th number. Many don’t know where to start!

[@rodfulford4306]

7+99*4= 7+396 = 403

[@Hi-rw8vr]

Use nth term. We know it has 4n as it is going up by 4 each time. 7 is 3 more than 4, 11 is 3 more than 8, etc. Therefore, the sequence is 4n+3. 4x100=400 400+3=403

[@ItsVideos]

Every integer from 1 to 100 is mapped to 4 times itself plus 3. 100*4+3=403 🙂 A+ 100% ⭐⭐⭐

[@uklawrence]

That's how I worked it out!

[@aryusure1943]

I would have added this remark to this teaching with all due respect. (n - 1) in the formula means that there is 99 "d" between the first number and the 100th in this sequence. I inferred it but it's not a small detail if one wants to figure out the signification of the formula. If I have a sequence of 10 numbers and I'm looking for the 10th I have to know that there are not 10 times the gap (d) but only 9. Anyway, thanks for this formula. I'll try to remember it. :)

[@enderthexenocide760]

I didn't know the formula but I did logic my way to a very close approximation. I figured since the common difference was 4 and we were looking for the 100th term, 400 would be close to, if not exactly, the answer. Off by 3 so not too bad considering I didn't know how to properly solve it.

[@RockSolid87]

Love your channel!!

[@Mike80097]

Me too

[@starryk79]

hm i made one probably common mistake by getting to 407 which is the 101st element in that sequence. When i figured out that the difference is always 4 i simply came to the conclusion that the 100th element must be 100 * 4 + 7 and yeah there i made the mistake not to subtract the 4 from the 7.

[@russelllomando8460]

interesting. thanks. so much easier than my find. 100 positions = 400 +7=407 minus first 4 increase - 403. yours is better. also (99 x 4) + 7 - 403

[@quigonkenny]

403 x = 3+4n

[@panlomito]

Many will know where to start, there are multiple starting points: 3 + 100x4 = 403 or 7 + 99x4 = 403

[@enderthexenocide760]

well many people don't know where that 3 comes from so he's correct that many people won't know how to begin this without brute forcing it.

[@panlomito]

@@enderthexenocide760 Just read the reactions, many do know (of course) !

[@enderthexenocide760]

@@panlomito you do realize that the entire population isn't commenting on these videos don't you? Many people will not know how to begin this type of problem, that is indisputable. Just because "many" people, whatever that means to you (there are not even many comments though), will know does not imply that many won't.

[@eduardoroman2691]

x = 4n + 3 = 403

[@MattGilliesCwnAnnwn]

7+4(n-1)

[@kennethwright870]

(4*100)+3=403

[@Eleuthero5]

Start with 7 and go up by fours. So ... 99 * 4 + 7 = 403.

[@GaryBricaultLive]

Your formula is incorrect. The problem presented clearly stated that the beginning number is 7 and not 3. This represents the 1st number in the series. For each "n" to the 100th instance, an addition 99 numbers increased by 4 would have to be included in the number series. Therefore the solution formula should be; 7 + (4 * 99) = 403 where 7 is the initial value, each successive increment is 4, and repeated 99 times, with 403 as the 100th number in the series.

[@Kleermaker1000]

This makes more sense to me.

[@kimobrien.]

3+4x=t where x is the sequential number.

[@aryusure1943]

I was close but instead of adding 7 to my result I substracted 7. :( But of course there is an easy way to solve this sequence but it's not a short cut. You write all the numbers from 1 to 100 and you fill the blanks.

[@dexiexo2199]

I thought it was some hard tricky math when I saw the title, after I clicked I was like “oh really”

[@samswift4921]

403 but I did it too fast in my head

[@dwaipayandattaroy9801]

Easy for denominator of 201, it's 807, 😁

[@marilynmarilyn747]

Well I did it in my head and came up with 43 so I guess I had part of the concept lol

[@b213videoz]

Why must it start with 1 ?!! No good, offsets should be 0-based 😊 so offset=99 (100-1), step=4, start=7 ...and the value = start + (offset * step) = 7 + (99 * 4) = 403

[@axelinedgelord4459]

took me like, a minute. 403.

[@Kylee-v1e]

too fast