How to solve simultaneous equations by substitution

Поделиться
HTML-код
  • Опубликовано: 30 ноя 2024

Комментарии • 174

  • @rhonikathom330
    @rhonikathom330 3 года назад +2

    is two coordinates necessary

    • @3minutemaths
      @3minutemaths  3 года назад +1

      Hi - yes, with these types of questions. Although you might also come across 'proof of tangent,' where there is just one set of coordinates. Here's a video that might help: ruclips.net/p/PLPglScc3TJ-PlCaMY8JMMoRhGefdYB8N9. All very best S :-)

  • @BeintheEpicArmy
    @BeintheEpicArmy 7 лет назад +49

    This can be up to 7 marks on a GCSE paper out of 80, which is too high an amount for my liking. If this is on the non-calc today you've saved my life

    • @Unknown-si8yx
      @Unknown-si8yx 7 лет назад +4

      Sarcastic Brit it was in the non calc as a 4 marker

  • @aminawashere7902
    @aminawashere7902 8 лет назад +49

    i thought i was just dumb but after this vid ive lost the will to do all this stuff smh - your video is really good it just my stupid brain

    • @3minutemaths
      @3minutemaths  8 лет назад +4

      Hi - it's great that you're watching the videos and trying to work through. All very best with your studies :-)

    • @adhamghaly7256
      @adhamghaly7256 6 лет назад +8

      dude sometimes you just gotta relax you know. the reason its difficult for you is because you're over complicating things for yourself, trust me i was like that too until i learned how to relax. you know i struggled with this alot until i found out the only thing i was missing was the quadratic formula. and then i aced this, you can too :)

  • @carlaalleng3433
    @carlaalleng3433 7 лет назад +27

    great explanation. but you need to write a little bigger.

  • @stunninglad1
    @stunninglad1 9 лет назад +8

    Perhaps a little mini quiz at the end of your lessons would be an idea. Students nod in agreement when a qualified teacher, like yourself, explains it all, but let's see their grimacing begin when they're put to the test.

  • @josephparsons6074
    @josephparsons6074 9 лет назад +8

    Thanks Simon, I now understand how to do this equation. This really threw me in my exam. Nevertheless, thanks for dedicating a video to answer my question :)

    • @3minutemaths
      @3minutemaths  9 лет назад +3

      Joseph Parsons You're very welcome and all best with your studies :-)

    • @josephparsons6074
      @josephparsons6074 9 лет назад +1

      Simon Deacon​ Thanks for you help and thanks.

  • @Ben.N
    @Ben.N 5 лет назад +26

    Damn, that's the exact same question on my homework

  • @Jade-ot9rs
    @Jade-ot9rs 7 лет назад +1

    Totally forgot to ask my tutor about this and have my exam tomorrow, this has helped me so much! Thank you :)

  • @tujihayder657
    @tujihayder657 6 лет назад +1

    You taught me what I didn't even know it's existence ! Much respect!Thanks for sharing from your knowledge.

  • @elliottcooksey6886
    @elliottcooksey6886 6 лет назад +2

    Great vid, my problem is the rearrange or substitution part, any tips? In the GCSEs I need to get this right as I am projected an 8

  • @animatedgaming1235
    @animatedgaming1235 8 лет назад +1

    Thanks,you helped me ALIOT.i got a a* on math for GCSE

    • @Anonymous-bh7gl
      @Anonymous-bh7gl 8 лет назад

      Congratulation . I Am sitting for IGCSE this year hope i get a* in math too

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi - Glad to help and all best for your results :-)

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi - that's great and glad to help :-)

  • @sadehassan4146
    @sadehassan4146 8 лет назад +1

    thanks alot for both sacrificing your time helped us. and again thanks.

    • @3minutemaths
      @3minutemaths  8 лет назад +1

      +Sade Hassan - Glad to help and all best S :-)

  • @KobinaTAmp
    @KobinaTAmp 4 года назад +1

    Thanks for the tutorial! It really helped

  • @Angiewallenstein
    @Angiewallenstein 7 лет назад +9

    Thank you!

  • @oliviaadams4420
    @oliviaadams4420 8 лет назад +1

    MY BRAIN!!! I'm in year 8 would I need this for my year? And thanks for helping

    • @3minutemaths
      @3minutemaths  8 лет назад +1

      Lol, no worries and glad to help. This topic tends to be fairly advanced so I don't think you'll come across it in year 8 .... more likely 10 or 11? Great that you're watching the videos now though and all best with your studies :-)

    • @xofyu
      @xofyu 7 лет назад

      last year pinhead

  • @KabzOG
    @KabzOG 7 лет назад

    Hi Simon, can you please help me with this question?
    5x - y = 5
    2y - x^2 = 11

  • @freewilliam93
    @freewilliam93 5 лет назад +2

    2:03 please make sure your letters are written correctly. was distracted looked back and had to rewind, yea easy solution but still.

  • @samirsafe9364
    @samirsafe9364 7 лет назад

    yaaah. .you aare truly a genuine genious...thank you very much..

  • @chiranthp7060
    @chiranthp7060 7 лет назад

    I learned how to do problem for my maths worksheet and thank you

  • @sampsterjedi1821
    @sampsterjedi1821 7 лет назад

    Thanks! helped a lot with my homework.

  • @mekseb8439
    @mekseb8439 7 лет назад +6

    The only explanation I understand

  • @awesomepeople5651
    @awesomepeople5651 8 лет назад

    You earned a new subscriber!

  • @BobBob-uv9fq
    @BobBob-uv9fq 3 года назад

    I’m 53 so just started again ,are these skills given during the coarse of a term ,I assume if the questions are being asked then the coarse would cover all necessary skills%?

    • @3minutemaths
      @3minutemaths  3 года назад

      Hi - Great that you’re working on these and please do let me know if you need any help. Here’s a post that might be a good starting point: www.3minutemaths.co.uk/gcse-revision-by-grade/. All very best S

    • @BobBob-uv9fq
      @BobBob-uv9fq 3 года назад

      I have a teacher I go to ,making decent progress but just started ,I am quite enjoying it

    • @3minutemaths
      @3minutemaths  3 года назад

      @@BobBob-uv9fq That’s great and all best with your studies :-)

  • @stephendurden9000
    @stephendurden9000 8 лет назад

    Absolute star👍🏻 real life saver mate

  • @adhamghaly7256
    @adhamghaly7256 6 лет назад +1

    thanks so much dude this saved me big time :) i owe you one.

  • @lujjaleel3621
    @lujjaleel3621 8 лет назад

    Great video.Can I use the completing square method instead of the formula method ?

    • @3minutemaths
      @3minutemaths  8 лет назад

      +luj jaleel - Hi - great question - yes, you could but you'd need to deal with the 2xsquared, as completing the square only works with a single value of xsquared. If you divide through by 2 you'd get:
      xsquared - 2x - 5/2 = 0
      (x-1)^2 - 7/2 = 0 (I've missed a couple of steps here - is that OK?)
      x = 1 + root7/2
      x = 2.87
      x=1-root7/2
      x = -0.87
      I hope that's all OK ... if you need a full breakdown happy to help.
      All best
      S

  • @Invisible667
    @Invisible667 8 лет назад

    Great video. Helped me a lot

    • @3minutemaths
      @3minutemaths  8 лет назад

      +Erkan Keceli - Glad to help and all best S :-)

  • @ladysai13
    @ladysai13 3 года назад

    Thanks a lot it helped me alot

    • @3minutemaths
      @3minutemaths  3 года назад

      That’s great and glad to help. All best S :-)

  • @laurengrace7090
    @laurengrace7090 8 лет назад +3

    Thank you for helping me, I'm in year 7, and it really helped me a lot.

  • @glitterandglamtoys1237
    @glitterandglamtoys1237 3 года назад

    so good thanks for the help

  • @Ali.nasaar
    @Ali.nasaar 7 лет назад

    Why don't we just use the mode 5, 3 in Casio fx991 calculators to come out with the two x coordinates instead of using the formula?

  • @Ali.nasaar
    @Ali.nasaar 7 лет назад

    Thx it's very useful and ur clear to understand!

  • @sorayaf894
    @sorayaf894 4 года назад

    hey, this video was very helpful thank you! i just have a question for one of my tests and i tried to look every were but still cant find an answer. the question is 2p^2 - p = 15. i know p=3 because i worked it out kind of guessing but i want to know how you would come to an answer like this in case i have questions with higher numbers. I know that p is three but can one of you guys tell me without being smart -so it is easy for my to understand- how to do it?

  • @saddat14
    @saddat14 8 лет назад

    Hello sir, i did factoring instead of the quadratic formula and my 2 sol are x=3 and x=-1 or we are supposed to use quadratic formula

    • @albertwayable
      @albertwayable 8 лет назад

      ITS A METHOD OF UR CHOICE, U CAN USE WHAT U WANT. BUT QUADRATIC FORMULA IS APPLICABLE TO ALL EQUATIONS WHAT EVER U HAVE, IF U CANT FACTOR THEM , USE THE QF.

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi ... you've got to be a little careful with using the quadratic formula. It only relates to quadratic equations, where you have an xsquared term, an x term and a number. In the example I've got a circle and the formula won't work - sorry! :-) .

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi - as mentioned to Sadat - unfortunately the formula won't work with this example as it's a circle. It is a good idea to use QF but you need to make sure it's for solving a quadratic equation. All best S :-)

    • @saddat14
      @saddat14 8 лет назад

      Thanks

    • @xofyu
      @xofyu 7 лет назад

      ya quadratic is borringer

  • @thebarkaysfan1100
    @thebarkaysfan1100 6 лет назад

    At 4:14 Why cant you use another way instead of using a Quadratic Formula to cancel things? Like Factorising?

    • @3minutemaths
      @3minutemaths  6 лет назад

      Hi - ... unfortunately you wouldn't be able to find the factors of 2xsquared - 4x - 5 by trial and error. It's a little difficult to know when to use Quad formula (or completing the square), but generally:
      - when there's a number in front of the xsquared
      - if the question says something like '3 sig fig or 2 decimal places.'
      Hope that helps and all best S

  • @lamerauna3814
    @lamerauna3814 5 лет назад

    Actually help thanks hope I pass tomorrow test

  • @Clara-go5sp
    @Clara-go5sp 3 года назад

    If you have x (y) equals 392 and x divided by y equals 8 then how do I do that

    • @3minutemaths
      @3minutemaths  3 года назад

      Hi
      If xy = 392 and x/y = 8 (which also means x = 8y) then
      Change the value of x
      (8y)y = 392
      So
      8ysquared = 392
      Divide by 8
      ysquared = 49
      Then square root
      y must equal +7 or -7
      You can then use these to work out x
      x = 8y
      So x = 8(7) = 56
      Or x = 8(-7) = 56
      Hope that helps and all very best S

  • @chetnajoshi7512
    @chetnajoshi7512 7 лет назад

    Your vedio was good I still didn'tunderstand.
    Thankyou.

  • @KittyPikaChu
    @KittyPikaChu 5 лет назад

    Thank you king

  • @joshwealleans2831
    @joshwealleans2831 7 лет назад

    Cheers pal very much helped with my hw👍🏻

  • @bantercomedy4947
    @bantercomedy4947 8 лет назад

    is there a video on completing the square? Otherwise very helpful.

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi - here's the latest playlist on completing the square ruclips.net/p/PLPglScc3TJ-PStRNnoKPCqhJAzBPNv3y-. All best S :-)

  • @MegaSquiff
    @MegaSquiff 3 года назад

    Well explained ,a big thanks to you. Subbed!

  • @patrickmcdonald8065
    @patrickmcdonald8065 5 лет назад

    Big help thanks

  • @rukiyezahitler2990
    @rukiyezahitler2990 6 лет назад +1

    Excelent!
    Thank you simon

  • @utilizeolly8491
    @utilizeolly8491 7 лет назад +6

    This is in my foundation paper wtaf😂

  • @janunarayan11.11
    @janunarayan11.11 7 лет назад

    Thanks! Such a great explanation! Love the way you did your 8 at 7:30! :)

  • @taliabayes4645
    @taliabayes4645 7 лет назад

    What would I do if the equations were for example..
    4x^2+4y^2=25
    2y=2x+1
    ???

    • @3minutemaths
      @3minutemaths  7 лет назад +1

      Hi - perhaps the easiest would be to divide the second equation through by 2:
      y = x + 1/2 and then substitute as video. All best S :-)

    • @taliabayes4645
      @taliabayes4645 7 лет назад

      Simon Deacon great! Thank you!

    • @sonitclef8675
      @sonitclef8675 5 лет назад

      Tou are screwed is your answer

  • @strongstylewrestling3643
    @strongstylewrestling3643 7 лет назад

    Great channel! This helped me alot! thnx!

  • @dharveyftw7349
    @dharveyftw7349 3 года назад

    (2 +- 14) / 4 = 4 or 3
    But in my answer sheet, it says x is either 3, or -4
    Why?
    y=x+1
    x^2 + y^2 = 25

    • @3minutemaths
      @3minutemaths  3 года назад +1

      Hi
      I hope this will read OK:
      Substitute y=x+1
      x^2 + (x + 1)(x + 1) = 25
      Expand
      x^2 + x^2 + 2x + 1 = 25
      2x^2 + 2x - 24 = 0
      It’s easier to divide everything by 2
      x^2 + x - 12 = 0
      Factorise
      (x - 3)(x + 4) = 0
      So x = 3, x = -4
      Hope this helps and all best S :-)

    • @dharveyftw7349
      @dharveyftw7349 3 года назад

      @@3minutemaths this help me, thanks. Though from reading the solution, I realize I must put more time into factorization. That's why I couldn't get the answer correct, I wasn't factoising properly.

    • @3minutemaths
      @3minutemaths  3 года назад +1

      @@dharveyftw7349 Hi - no worries and glad to help. Here’s a link to a playlist on factorising, that might be useful: ruclips.net/p/PLPglScc3TJ-PgEVPNvC2blKA0zlg5hQVT. All very best S

  • @sammyvolchek9667
    @sammyvolchek9667 8 лет назад

    This was really helpful. You explained it really clearly and understandable. Thank you very much!! :)

  • @tawheedislam8735
    @tawheedislam8735 7 лет назад

    I'm in year 7 and I have to do this!!

  • @aminahagha1160
    @aminahagha1160 8 лет назад

    very helpful thanks alot ☺

  • @ragavanmanandaswamy4837
    @ragavanmanandaswamy4837 8 лет назад

    thank for posting
    it help for solving out problems

  • @belleviehanan434
    @belleviehanan434 3 года назад

    thank u so much !!

  • @rafidrahmanchowdhury8677
    @rafidrahmanchowdhury8677 8 лет назад

    Thank You , it hepled a lot !

    • @3minutemaths
      @3minutemaths  8 лет назад

      That's great and glad to help - all best S :-)

  • @edmetpassion8156
    @edmetpassion8156 5 лет назад

    Good job

  • @tituslatchmansingh4706
    @tituslatchmansingh4706 6 лет назад

    very good video 💯

  • @sonitclef8675
    @sonitclef8675 5 лет назад +1

    What if there is a 2x^2
    This is my quastion:
    2x +y =5
    2x^2 +y^2 =1148

    • @aameame1437
      @aameame1437 5 лет назад

      That can be done by using demolition method .

  • @brandonatkins8244
    @brandonatkins8244 8 лет назад

    great video!

  • @nannaeighteen8464
    @nannaeighteen8464 8 лет назад +2

    You explain the working of the examples really well but your writing is very difficult to read.

  • @mustaqeezahmad5591
    @mustaqeezahmad5591 8 лет назад

    hello please can you solve this problem :
    3X^2+2xy+y^2=11;
    3x-4y=19

  • @muhiyadinabdi9247
    @muhiyadinabdi9247 7 лет назад +1

    Can someone please do this question (6mark)
    y=2X^2
    y=20-3x

  • @timtran333
    @timtran333 5 лет назад

    Good thanks

  • @GandalfGaming2144
    @GandalfGaming2144 7 лет назад +3

    wait when you get the quadratic why not factorise

  • @dumbrepellent-4327
    @dumbrepellent-4327 8 лет назад

    Thank you 💚

    • @3minutemaths
      @3minutemaths  8 лет назад

      +Shiann - - Glad to help and all best S :-)

  • @charlottegreen7024
    @charlottegreen7024 8 лет назад

    SO USEFUL!!! Thank you so much (:

  • @natsudragoniel9235
    @natsudragoniel9235 7 лет назад

    thx realy helped

  • @finnohara5318
    @finnohara5318 4 года назад +1

    genius

  • @tshwarelomatinketsa3508
    @tshwarelomatinketsa3508 7 лет назад +2

    thanks a lot understandable

  • @Ngairah
    @Ngairah 6 лет назад

    Thanks

  • @inthebackwiththerabbish
    @inthebackwiththerabbish 7 лет назад

    The coordinates are the x values written either way

  • @josephkakoma1322
    @josephkakoma1322 4 года назад

    Now what if it is like this;3y=5 -2x , y power 2 = xy+5

    • @3minutemaths
      @3minutemaths  4 года назад

      Hi - here you go: ruclips.net/video/enXfJST5ZMk/видео.html. Hope it helps and all best S

  • @BobBob-uv9fq
    @BobBob-uv9fq 3 года назад

    Could u not square the route? Why

    • @3minutemaths
      @3minutemaths  3 года назад

      Hi - yes, you could solve by completing the square ... although it might be potentially a little more difficult. Here's a playlist that might be of interest: ruclips.net/p/PLPglScc3TJ-PJtiMqvASoTTGE7i9FQhJV. Best S

  • @MusixandRandom
    @MusixandRandom 4 года назад

    why cant you take x=2-y instead of y=2-x

    • @3minutemaths
      @3minutemaths  4 года назад +1

      Ryan 901 Hi - you could do either. Best S

  • @kennethjoseph8360
    @kennethjoseph8360 6 лет назад

    U for forgot -4 when applying the quadratic formula

    • @3minutemaths
      @3minutemaths  6 лет назад

      Hi - at 4.54? It's -4 but the formula asks for -b ... so - (-4) is +4.
      Hope that's OK, best S

    • @kennethjoseph8360
      @kennethjoseph8360 6 лет назад

      Ooohh. Thank you that really confused me😂 wish me luck for my finals

    • @3minutemaths
      @3minutemaths  6 лет назад

      All best!

  • @caanonuugfilmsacademy8794
    @caanonuugfilmsacademy8794 6 лет назад

    hello sir why did u put - 4 as quadratic equation then it was -4 and u solved +16 it should be -16

    • @3minutemaths
      @3minutemaths  6 лет назад

      Hi - please can you give me the time point?

  • @GandalfGaming2144
    @GandalfGaming2144 7 лет назад

    this showed up on edexcel paper 1 i think i could get a few marks on it

  • @ahmedkadhim4959
    @ahmedkadhim4959 8 лет назад

    Can u solve on other way

    • @3minutemaths
      @3minutemaths  8 лет назад

      +Adam Ahmed - Not really ... substitution is the way to go with these types of questions. There's a few more examples in this playlist ruclips.net/p/PLPglScc3TJ-PhJ6J33bzvWJBQUQKg-LZ4. All best S :-)

  • @f3r178
    @f3r178 5 лет назад

    Are the videos from 2006 not working??

  • @sunainapanthee2732
    @sunainapanthee2732 7 лет назад

    2x+3÷y=16
    3x-2÷y=-2 could u pls tell me its solution

  • @bepatient9865
    @bepatient9865 7 лет назад +2

    you x seems like 2

  • @danielkagwanyi1934
    @danielkagwanyi1934 6 лет назад

    wow you did it BETTER

  • @faxx8832
    @faxx8832 6 лет назад

    I'm first year average rank and this is on out test with no keys and no answers.

  • @claudinefisher5311
    @claudinefisher5311 4 года назад

    ko

  • @johnkramer5886
    @johnkramer5886 6 лет назад

    We have this on the non calculator paper. No way is anyone going to work it out in 10 minutes with quadratic formula

    • @3minutemaths
      @3minutemaths  6 лет назад

      Hi - if this kind of question was on the non calc, you shouldn't need the formula and the values would usually be whole numbers or fairly simple fractions. Best S

  • @BobBob-uv9fq
    @BobBob-uv9fq 3 года назад

    With teacher easy peasy ,without teacher greasy cheesy

  • @shelly_rose6815
    @shelly_rose6815 7 лет назад

    when I worked it on calculator, I got x=7.32 or x=-5.32

    • @3minutemaths
      @3minutemaths  7 лет назад

      Hi - not sure how that happened ... :-)

    • @shelly_rose6815
      @shelly_rose6815 7 лет назад

      Simon Deacon
      its OK though, I'm probably wrong anyway. thanks

  • @tommyriordan870
    @tommyriordan870 7 лет назад

    chap its 1.87 not 2.87

  • @yasminsmith4037
    @yasminsmith4037 8 лет назад

    My exam is tomorrow! :-0

  • @jasminejas8307
    @jasminejas8307 8 лет назад

    The quadratics bit really confused me

    • @3minutemaths
      @3minutemaths  8 лет назад

      Hi - yes, it can be a little tricky. Here's a playlist on solving quadratics, using the formula, that might help: ruclips.net/p/PLPglScc3TJ-O2zVEZXTVuP-o8WYm93xyd. All best S :-)

  • @jasmeetkaur5775
    @jasmeetkaur5775 7 лет назад +2

    Lmao we r learning this in year 7....when will I ever need thks in lyf
    ?

    • @Jack-bg4jp
      @Jack-bg4jp 7 лет назад +5

      its not about needing it its to show you can learn things and do them for later on in life

  • @gray2543
    @gray2543 5 лет назад

    Achew

  • @tawheedislam8735
    @tawheedislam8735 7 лет назад

    I have no clue how to do this

  • @nurulnasuha1249
    @nurulnasuha1249 3 года назад

    I watch this during my exam,,is this called cheat?

  • @zzey
    @zzey 5 лет назад +1

    *Earape has entered the chat*

  • @itsaya2057
    @itsaya2057 8 лет назад

    maths exam today

  • @zoroastrianisticzoro297
    @zoroastrianisticzoro297 8 лет назад +1

    Lost me but thanks

    • @3minutemaths
      @3minutemaths  8 лет назад +2

      Yes, these can get a little complex - great that you've had a go though :-)

  • @smdmadarsa2857
    @smdmadarsa2857 7 лет назад

    big size sir

  • @t.v.y7383
    @t.v.y7383 3 года назад

    Yuu

  • @ramking7869
    @ramking7869 7 лет назад

    lol i am gr.8 and
    i know this