Find the nth term in a Quadratic Sequence

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  • Опубліковано 3 чер 2018
  • How to find a formula for the nth term in a quadratic sequence

КОМЕНТАРІ • 168

  • @divangrobler2356
    @divangrobler2356 3 роки тому +11

    I've been struggling with this for a full year! Thanks so much this finally makes sense!

  • @krishypo3468
    @krishypo3468 5 років тому +24

    Thaaaankkk youuu I was definitely going to fail this test thx for this explanation

    • @MathsWithJay
      @MathsWithJay  4 роки тому +2

      @Krishna Pol: Thank you! Hope your test went well!

  • @navin7560
    @navin7560 5 років тому +51

    this helped me impress my maths teacher ty so much

    • @MathsWithJay
      @MathsWithJay  5 років тому +6

      @navin navin: That's great! Thank you!

  • @bluebuddy6191
    @bluebuddy6191 4 роки тому +37

    Thanks I need this for my GCSE

  • @yimran5052
    @yimran5052 3 роки тому +8

    The explanation was terrific!
    Wonderful Job Frau Jay!

  • @RinxOwnsYou
    @RinxOwnsYou Рік тому +2

    This was so confusing to me, you made it so easy to understand, thanks for making this

  • @geraldillo
    @geraldillo 3 роки тому +3

    Thank you for sharing your knowledge! Are there similar methods to find higher degree series as well?

  • @seanhiggins609
    @seanhiggins609 3 роки тому +5

    I must be unteachable when you put 8n² in the table and got -32 I was like how

  • @Saturos_Wifey
    @Saturos_Wifey Рік тому

    watching this one night before igcse maths exam cuz none of my teachers helped... thank you for saving my life 🙏

  • @niv_g
    @niv_g 2 роки тому +3

    helped a lot im doing IGCSE extended maths and this really did help, thank you :)

    • @MathsWithJay
      @MathsWithJay  2 роки тому +1

      You're very welcome!

    • @poplil3934
      @poplil3934 2 роки тому

      @@MathsWithJay Hello, i wanted to ask, why went finding the an, we needed to divide the 16 by 2. pls and thank you.
      Edit: an^2

    • @hirokazuma8979
      @hirokazuma8979 2 роки тому

      @@poplil3934 we apparently need to divide by 2 every time

  • @gkinlen
    @gkinlen 3 роки тому

    Best explanation and step by step working of topic Thanks

  • @satorujjk
    @satorujjk 2 роки тому +1

    4:54 , it doesn't mean you've gone wrong, it just shows that there isn't a bn , so the equation would be an^2+c. I have come across a question where the answer is a quadratic but is in the form of n^2+c instead of n^2+bn+c

    • @MathsWithJay
      @MathsWithJay  2 роки тому

      Yes, you're right - that is another possibility

  • @anirudhmor2094
    @anirudhmor2094 5 років тому +2

    awesome your the best math like rananjum

  • @babua077
    @babua077 4 роки тому +1

    Great vid. Thx for the help.

  • @beetlejuice5484
    @beetlejuice5484 5 років тому +11

    Why is it -8 I am so confused it was positive 8 before

    • @MathsWithJay
      @MathsWithJay  5 років тому +4

      @Davey: We have found the first part of the formula is 8n^2, so we can subtract that to leave the rest which will be linear. Looking at a simpler example: 3, 8, 15, 24,...The differences go up in 2's, so we know that the formula starts with n^2, so we subtract 1, 4, 9, 16 respectively to leave 2, 4, 6, 8 and can see that the linear formula for these numbers is 2n. So now we can put the two formulas together to get n^2 + 2n

    • @lowlandplum5569
      @lowlandplum5569 3 роки тому

      @@MathsWithJay i still dont get how this makes it a minus

  • @elijaha6886
    @elijaha6886 4 роки тому +1

    This helped me a lot thanks!!!

  • @tanayjyotchawla6259
    @tanayjyotchawla6259 3 роки тому +1

    This is the second time I am watching this vid and it is still helpful

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      You may like to look at this: ua-cam.com/video/5iLAGcz4Vfk/v-deo.html

  • @13cicc
    @13cicc 2 роки тому

    Best video on the topic!

  • @someone-tn3dc
    @someone-tn3dc Рік тому

    u slayed fr fr

  • @afsanarahman8248
    @afsanarahman8248 4 роки тому +1

    Hello I love 💓 you’re explanation Tysm

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      @Afsana Rahman: You’re welcome 😊

  • @joeharris8895
    @joeharris8895 5 років тому +2

    Great vid my brudda

  • @sneak_ios8704
    @sneak_ios8704 3 роки тому

    Thank you do much i didnt learned anything at all but dont worry im subscribe and i like you because all your other vedios helped me and you helped makr my teacher proud by me

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      Do you have a question about this video?

  • @meowLy_
    @meowLy_ 2 роки тому

    aa tysm! greatly appreciated :)

  • @alicorntube600
    @alicorntube600 2 роки тому

    Thank you so much I need this to finish my homework

  • @zobbs
    @zobbs 2 роки тому

    Thank you very much Jay

  • @Fiercekiller-cs3tq
    @Fiercekiller-cs3tq 3 роки тому +1

    Thank you so much ♥️

  • @prasunpradip6964
    @prasunpradip6964 3 роки тому +1

    tomorrow i have maths exam and this topic was left out ....thanks

  • @seanzzz3068
    @seanzzz3068 6 років тому +2

    Good Job thanks for you kind help and tutorial Keep it Up !😉

  • @yasserelbasyouni9751
    @yasserelbasyouni9751 4 роки тому +2

    you deserve a LIKE :D

  • @itz_fiyin
    @itz_fiyin Рік тому

    Thank you, helped me do my homework correctly 🎉

  • @KINGABDUL99
    @KINGABDUL99 2 роки тому +1

    Thank u so much.

  • @shafay3262
    @shafay3262 3 роки тому

    does it have to be divide by 2 each time? or is that only for this specific quadratic equation?

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      You could try it yourself: what happens with the simplest example: 1, 4, 9, 16, 25,...What are the second differences? Then try multiplying up by an integer, say 10, so you get 10, 40, 90, 160, 250,...What are the second differences? Can you answer your question?

    • @shafay3262
      @shafay3262 3 роки тому

      @@MathsWithJay Thanks! This video really helped me with my school homework.

  • @richardcao7390
    @richardcao7390 3 роки тому +1

    Got a sequence that involves n^3 and took me 4 difference of sum to get same ones... how would I convert the amount of times it takes to get a common difference to the power that I am looking for?

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      It should be 3 rows of differences to get n^3

    • @richardcao7390
      @richardcao7390 3 роки тому

      Maths with Jay why do u divide it by 6 when it's 3, and divide by 2 when it's 2? what about n^4 ._.

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      Maybe you will be able to work out the pattern....just try the simplest sequence of powers of 4: 1, 16, 81, 256, 625, 1296, and what is the 4th difference? Then the pattern should emerge...

  • @cipherunity
    @cipherunity 6 років тому +3

    Interesting

  • @koirblx2503
    @koirblx2503 3 роки тому +1

    im subbing.

  • @hari0301
    @hari0301 4 роки тому +1

    what if when you find the an^2 it becomes negative automatically, like -8n^2, Then is it 8n^2?

    • @MathsWithJay
      @MathsWithJay  4 роки тому +1

      @Hari: Why would you change the sign from negative to positive?

    • @LinkNS
      @LinkNS 4 роки тому

      i mean if that happened then you would have --8n^2 so it would become positive. but im not 100% sure

    • @sonalhattangadi2486
      @sonalhattangadi2486 2 роки тому

      It doesn’t become minus, the sign was there just to signify that it is being subtracted from the other sequence

  • @ahmedguessad4759
    @ahmedguessad4759 3 роки тому +1

    Thank you so mutch

  • @nadirsajid448
    @nadirsajid448 4 роки тому

    What if the difference you get (when finding bn+c),is different ?

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      @Nadir Sajid: What is your sequence?

  • @hello5810
    @hello5810 3 місяці тому

    thank you !

  • @randompersonp119
    @randompersonp119 3 роки тому

    Do we always have divide by 2 or does it change?🤔

  • @Exotic-zj2di
    @Exotic-zj2di 2 роки тому

    Hi, how do i determine which term has the value given to me using the formula?

  • @TheRealBleach
    @TheRealBleach 4 роки тому +1

    Thanks

  • @poriccrompton
    @poriccrompton 3 роки тому

    Right I’ve done this for like 2 hours on the same question pretty sure I’m doing something stupid what’s the nth term for to 1, 3, 6, 10, 15, 21

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      This method will work....have you worked out the first stage yet?

  • @AP-vy9bc
    @AP-vy9bc 4 роки тому

    I got -2 and +3 would that also be right?

  • @nicholusmalifa2263
    @nicholusmalifa2263 4 роки тому

    Why do you do minus 8 instead of positive 8 for 8n^2???

  • @thenormalkid3781
    @thenormalkid3781 2 роки тому

    ty bro

  • @kjono4611
    @kjono4611 4 роки тому

    If you had to find the differences 4 times before they converge, would that mean the answer should be in the form an^4 + bn^3 + cn^2 + dn + e or should it just be an^2 + bn + c?
    The sequence is 1, 3 ,12, 39, 120, 316, ...
    which makes the differences 2, 9, 27, 81, 196
    and then 7, 18, 54, 115
    then 11, 36, 61
    then 25, 25
    If it should be the first option, do I just repeat the steps again and again or is there another way to do this?

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      Kieran, it's the first option. You could find the coefficient of n^4 first and so on.

  • @shawzabmahmood2073
    @shawzabmahmood2073 4 роки тому

    Thanks a lot!!!
    It is really really helping me! God bless you!! 😇😇

  • @mewa5842
    @mewa5842 4 роки тому +1

    I don’t get where you got + 2 from

  • @trulyross_
    @trulyross_ 4 роки тому

    What if you don't have the first 4 but instead the 2nd 3rd and 5th term only

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      @Ross: Have you been told what kind of sequence it is? (Linear, quadratic, ...)

    • @trulyross_
      @trulyross_ 4 роки тому

      @@MathsWithJayit's quadratic but don't worry i managed to solve it but thanks!

  • @webtree5171
    @webtree5171 3 роки тому

    @2:32, why do we divide it by 2??

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      Look at the simplest quadratic sequence, the square numbers: 1, 4, 9, 16, 25,... and work out the second differences....what do you get?

  • @chandrababuhansda54
    @chandrababuhansda54 4 роки тому

    I can't understand at the end that is( +2) concept .plss mam reply me

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      At what time in the video?

    • @chandrababuhansda54
      @chandrababuhansda54 3 роки тому

      @@MathsWithJay at 5:36, i mean c=2 is come from where

    • @MathsWithJay
      @MathsWithJay  3 роки тому +1

      -1+3=2 See ua-cam.com/video/vvayGlslby0/v-deo.html

  • @sirlordhobo1061
    @sirlordhobo1061 3 роки тому

    tysm

  • @Aisha-gd6dq
    @Aisha-gd6dq 3 роки тому

    Why do we make it 3n from 8n and how?

  • @hari0301
    @hari0301 4 роки тому +1

    what if the diffrence of the diffrence is 0

    • @MathsWithJay
      @MathsWithJay  4 роки тому +1

      @Hari 0: Which difference? The first or second?

  • @Yhman
    @Yhman 4 роки тому +1

    What if 8n squared is negative

    • @MathsWithJay
      @MathsWithJay  4 роки тому +2

      @Henry: Squaring would always give a positive number.

    • @Yhman
      @Yhman 4 роки тому +3

      @@MathsWithJay thanks really helpful

  • @K.DOT11
    @K.DOT11 4 роки тому

    What do you do when the differences are not the same? Plz help

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      Can you give an example?

    • @K.DOT11
      @K.DOT11 4 роки тому

      @@MathsWithJay I think it's known as a cubic sequence

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      Do the third set of differences come out to be the same as each other?

    • @K.DOT11
      @K.DOT11 4 роки тому

      @@MathsWithJay yes they do

    • @MathsWithJay
      @MathsWithJay  4 роки тому

      Then start by dividing the common difference by 6, that will give you the coefficient of the cubed term

  • @geronimalagunda7252
    @geronimalagunda7252 5 років тому +1

    what if the difference is 2

    • @MathsWithJay
      @MathsWithJay  5 років тому +1

      @Geronima: We always divide the difference by 2. So 2/2 = 1.

  • @saiclique
    @saiclique 3 роки тому

    How did it became -3? 5:03

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      We need to subtract 3 from -1 to get -4. See ua-cam.com/video/vvayGlslby0/v-deo.html

  • @lilah5592
    @lilah5592 Рік тому

    Is there a way to find the nth term of a quadratic sequence without using that formula?

    • @MathsWithJay
      @MathsWithJay  Рік тому

      A method that doesn't use a formula?

    • @lilah5592
      @lilah5592 Рік тому

      Like, a way that you can just calculate it without that formula, i learned it that way in high school but i forgot it

  • @dimaalhamoud
    @dimaalhamoud 8 місяців тому

  • @bobbydong1228
    @bobbydong1228 3 роки тому

    Pls can you help me out with 2,12,36,80.

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      That's harder than this one....it will involve cubing, not just squaring. If you haven't looked at cubic nth term yet, try writing each number in your pattern as a product of two numbers and look at 2 patterns...

  • @davidthomas4394
    @davidthomas4394 5 років тому +2

    Why do you divide 16 by 2

    • @MathsWithJay
      @MathsWithJay  5 років тому +1

      @David: At what time in the video?

    • @davidthomas4394
      @davidthomas4394 5 років тому +1

      2:36

    • @MathsWithJay
      @MathsWithJay  5 років тому +1

      @David: Think about the sequence of square numbers: 1, 4, 9, 16, 25,... The differences are 3, 5, 7, 9,... And the differences between the differences are 2...so we divide by 2 to get the number to multiply n^2

    • @davidthomas4394
      @davidthomas4394 5 років тому +2

      @@MathsWithJay Oh thanks

  • @amaniceh
    @amaniceh 2 роки тому

    why n=4?

    • @MathsWithJay
      @MathsWithJay  2 роки тому

      At what time in the video?

    • @amaniceh
      @amaniceh 2 роки тому

      @@MathsWithJay 5:50, i mean, why do we choose 4 of all numbers?

  • @joshreyes6158
    @joshreyes6158 3 роки тому

    Why is it plus 2

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      At what time in the video?

    • @joshreyes6158
      @joshreyes6158 3 роки тому

      5:30

    • @MathsWithJay
      @MathsWithJay  3 роки тому

      That part is looking at a linear sequence like: ua-cam.com/video/vvayGlslby0/v-deo.html

  • @ismaeelrafiq8028
    @ismaeelrafiq8028 3 роки тому

    My exam is tomorrow 😭

  • @t7yphaon16
    @t7yphaon16 5 років тому +1

    im vegan btw, very cool!