Solving Systems of Two Equations and Two Unknowns: Graphing, Substitution, and Elimination

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  • Опубликовано: 19 дек 2024

Комментарии • 64

  • @PhoenxFire
    @PhoenxFire 2 года назад +38

    We had a teacher with a doctorate in mathematics. I wish she could have explained this so easily to us. Sometimes having a doctorate does not make one a good teacher. Thanks for making this easier to understand!

    • @Carrymejane
      @Carrymejane 10 месяцев назад +5

      Actually they help u to solve the equation but not to help their student know how to understand the method 'concepts' well, they fail to understand each student. What you do now is just summarize from ur knowledge u got from ur teacher in school

  • @pianoboyedm4829
    @pianoboyedm4829 3 года назад +14

    thank you so much, my professor goes way too fast and never directly answers our questions, this helped our class out ALOT

    • @PhoenxFire
      @PhoenxFire 2 года назад +1

      I hate when that happens!

  • @CartoonKidOLLY
    @CartoonKidOLLY 2 года назад +6

    YAY it feels so good to understand the concepts and then get the problems right! I love you david!

  • @adityadhardwivedi634
    @adityadhardwivedi634 7 лет назад +53

    hello professor, when you're going to explain and start tutorials of calculus?
    Actually I am very much excited for your super easy tutorials. Thanks for your efforts.😃😊

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  7 лет назад +35

      don't worry they are coming soon! i have to get through geometry, more algebra, and trigonometry first, but within the year i'll get to calculus as well.

  • @avenger5339
    @avenger5339 2 года назад +3

    how can some one be so serious yet so lovable

  • @Carrymejane
    @Carrymejane 10 месяцев назад +1

    At school I was never able to understand the algebra method 'concepts' well, and I only realized it now. Because at school we only focus on solving equations. We don't understand in focus and detail the method 'concept' for doing this. We don't understand it in its entirety so we just 'know' that to solve the equation it is only necessary to just 'follow' what's teacher did. Actually teacher doesn't do something wrong they great at teaching but they fail to know whether each student automatically understands a method in detail

  • @AmmarShabaz-k1f
    @AmmarShabaz-k1f Месяц назад

    I love how simple you explain every thing that even a kid can understand math
    I really appreciate your work keep going
    Best of luck Sir and bro as well...

  • @scout0528
    @scout0528 3 года назад +17

    Bro you just saved me for my algebra quiz THANK YOU

  • @Concon-bu4bp
    @Concon-bu4bp 3 года назад +4

    Thanks dude. really enjoyed the manipulation followed by elimination, very cleaver way to approach the problem

  • @Regular_Decorated_Emergency
    @Regular_Decorated_Emergency 3 года назад +2

    Thanks so much! I finally understand what to do if you can’t subtract y from y to get 0!

  • @JoeDebunks
    @JoeDebunks Месяц назад

    Loving the videos as always professor.

  • @NickHope
    @NickHope 3 года назад +8

    I hope Penelope got paid overtime.

  • @reemyziz
    @reemyziz 4 года назад +3

    With checking comprehension, some y values don’t share a LSM. Can we multiple just one equation by a number so it matches the other?

  • @lexielea873
    @lexielea873 5 лет назад +3

    Holy shit you just taught me something that actually made sense for once and I’m so happy thank you

  • @sojulia1990
    @sojulia1990 5 лет назад +3

    Does this work on any function? Ex. Trig,Polynomial etc.

  • @vernie7882
    @vernie7882 4 года назад +1

    Can you explain where you got: if A = B and C = D then A + C = B + D and that it proves that it applies to the equation above? It makes sense by itself but how do I know if the two equations are in any way related to that logic and how it helps us in solving them?

    • @zerglin9000
      @zerglin9000 4 года назад +2

      For his example, A is the value of the first equation on the left of the equal sign and B is the value on the right.
      C is the value of the first equation on the left of the equal sign and D is the value on the right.
      so his two equations would be
      A = B
      C = D
      so if A=B and C=D, then A + C = B + D.
      This is relevant because we can use this information to do elimination, as we know that by adding or subtracting B on one side, we can add or subtract D on the other side to preserve the equality in our equations.
      it makes sense if you assign values to your variables. EX: when A is equal to 1, well A = B so 1 = B.
      This means when you are adding or subtracting one set of equations (A = B) to your other set of equations, you are preserving the original equality: eg not changing the values for your equations.

  • @MB-st6id
    @MB-st6id 3 года назад +2

    Amazing video

  • @SSP600
    @SSP600 3 года назад +2

    THANK YOU SO MUCH

  • @Vineet_Sri
    @Vineet_Sri 3 года назад +1

    Thanks for explaining this ❤️🔥

  • @UmbralCosmos
    @UmbralCosmos 4 месяца назад

    For those like me who couldn't understand WHY elimination works, here's a description I wrote for my small brain:
    So our intersection point is (8, 35/2)
    Now let us display elimination with the actual values of x and y.
    -3 . 8 + 2 . 35/2 = 11 = -24 + 35 = 11
    What we are doing is basically ADDING THE SAME VALUE TO BOTH SIDES OF THE EQUATION.
    5 . 8 - 2 . 35/2 = 5 = 40 - 35 = 5 We could just add 40 - 35 to the 11, instead of 5, after all 40 - 35 = 5
    +___________________
    Now check this out... 16 = 16
    So the process of elimination is just altering both sides of the equation, but using different forms of the same value for each side of the equals sign.

  • @azizghalib495
    @azizghalib495 6 лет назад +3

    Thank you professor. But could you elaborate on how does the logic of A+C=B+D relates to system of equations. In other words, what variable corresponds to which term.

    • @zerglin9000
      @zerglin9000 4 года назад +5

      For his example, A is the value of the first equation on the left of the equal sign and B is the value on the right.
      C is the value of the first equation on the left of the equal sign and D is the value on the right.
      so his two equations would be
      A = B
      C = D
      so if A=B and C=D, then A + C = B + D.
      This is relevant because we can use this information to do elimination, as we know that by adding or subtracting B on one side, we can add or subtract D on the other side to preserve the equality in our equations.

  • @OkSid300
    @OkSid300 9 месяцев назад

    Certainly a very productive lesson! But it would be great to have more real life examples.

  • @noemiflores5076
    @noemiflores5076 7 лет назад +6

    Hi professor Can you explain how to do Proportional and Non Proportianl? Thanks

  • @anusriiii
    @anusriiii 3 года назад +1

    You made it so easy.. thanks a ton

  • @maddyeldy2487
    @maddyeldy2487 2 года назад

    Thanks prof. Dave 👌

  • @marcodaniel5446
    @marcodaniel5446 5 лет назад +4

    I don’t know what’s going wrong but different methods are giving me different answers pls send help

  • @chloeledieff1462
    @chloeledieff1462 13 дней назад

    you have literally no idea how helpful this was (anyone here 2024?)

  • @nteproductions1083
    @nteproductions1083 3 года назад

    Could’ve used a lot of this yesterday on the PSAT

  • @captaingaz8705
    @captaingaz8705 3 года назад +1

    You need to make1 on comparison method

  • @johnymnemonic4657
    @johnymnemonic4657 Год назад +1

    There are more ways to solution.Cramer,s Rule and Gaussian ellimination.

  • @mar-ww3if
    @mar-ww3if 3 года назад

    professor i ended up with x=11 and y=-5 for the last comprehension example , are they alternative answers ?

    • @Teiwaz111
      @Teiwaz111 2 года назад

      6x + 6y = -24
      3x - 3y = 48
      Multiply the second equation by 2
      6x + 6y = -24
      6x - 6y = 96
      Now add them up to get rid of y
      12x + 0y = 72
      Solve for x
      x = 72/12
      x = 6
      Now use that in the second equation to solve for y
      3*6 - 3y = 48
      18 - 3y = 48
      -3y = 30
      -y = 10
      y = -10
      There are no alternative answers, as there is no alternative medicine - it either is an answer or not, it's either medicine or not.

    • @mar-ww3if
      @mar-ww3if 2 года назад

      @@Teiwaz111 you are kinda Late but thanks anyway

  • @Xboxlove1
    @Xboxlove1 6 лет назад +1

    well done

  • @anna.candrink7251
    @anna.candrink7251 Год назад +2

    You explained this like it's so easy💞
    Now, I feel dumb for not knowing how to solve these equations before🤡

  • @Mecha_Math
    @Mecha_Math 6 месяцев назад

    So good

  • @RedMetalSuit
    @RedMetalSuit Год назад

    How do you do elimination if the Y in both equations is negative?

    • @kcf29jdf30
      @kcf29jdf30 10 месяцев назад

      maybe multiply negatively? idk

  • @saniconeiljoshuac.2084
    @saniconeiljoshuac.2084 3 года назад

    What is the 2 equations are both positive?

  • @TranslaterMono
    @TranslaterMono Месяц назад

    Professor:Why is this useful?
    Me: To win SAT exam

  • @hajjjjrrrrrr
    @hajjjjrrrrrr 8 дней назад

    Could someone give explanation for comprehension’s solutions plssss guys

  • @chourouk-gr9qg
    @chourouk-gr9qg 5 месяцев назад

    ty

  • @kevinjohn1789
    @kevinjohn1789 5 лет назад +3

    Legend

  • @Jourvence777
    @Jourvence777 Год назад

    I've done it

  • @fazulrahmanhamidi8895
    @fazulrahmanhamidi8895 2 года назад

    Why write two equations to solve two unknowns? What is the reason?

    • @ProfessorDaveExplains
      @ProfessorDaveExplains  2 года назад +1

      It is impossible with only one.

    • @ta_ogboy9998
      @ta_ogboy9998 Год назад

      A solution to one equation won't mean it will be a solution to the other equation. You want to find a solution for both equations.

    • @Carrymejane
      @Carrymejane 11 месяцев назад

      It's just a reference to learn, like how a question make in the exam from the central

  • @Breadin
    @Breadin Год назад

    Please help I can't understand

  • @xeqqail3546
    @xeqqail3546 2 года назад

    For the
    5x + 2y = -18
    x - 7y = -11
    isn't the answer is
    x = -4
    y = -1
    ??

    • @trundlegaming8019
      @trundlegaming8019 2 года назад

      no its not, its just 1. Beacuse when you have 37y=37, its y=37/37 it dosent change to -37

  • @Ethiopianexposer
    @Ethiopianexposer 5 лет назад +3

    Jesus Christ, that was easy

  • @skullkid9475
    @skullkid9475 3 месяца назад

    I might be brain dead, this didnt help me even a little bit

  • @kimzlife5993
    @kimzlife5993 9 месяцев назад

    You explain too fast