Systems of equations with elimination (and manipulation) | High School Math | Khan Academy

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  • Опубликовано: 23 янв 2025

Комментарии • 97

  • @kefifixelhua7936
    @kefifixelhua7936 9 лет назад +44

    Finally, Khan Academy makes everything so much easier than hearing a math teacher in my school explain in some random gibberish and then ask us to do an example after 10 seconds and then the next day moving to some different lesson. This will totally save my grades, since I have a Math midterm exam on Friday

  • @joshthies6194
    @joshthies6194 7 лет назад +9

    I am in 8th grade and we learned this this is going to help me a lot in my finals thanks so much your the best

  • @xRABEE123x
    @xRABEE123x 14 лет назад +8

    OMG! THANK YOU SOOOO MUCH
    All the other tutorials were for adding and subracting and i taught thos were the only two ways you could do it and my exam is tommrow
    THANK YOUUUUUU!!!!

  • @polkadotocean4000
    @polkadotocean4000 11 лет назад +77

    This is so helpful! My math teacher is a complete idiot!

  • @nickboudreau821
    @nickboudreau821 12 лет назад +4

    very helpful! you explained it better than my teacher ever could

  • @thecowman4881
    @thecowman4881 11 лет назад +29

    you saved my grades

  • @mach5491
    @mach5491 8 лет назад +32

    Its three am I have a math test today and I am ready to die

  • @mikan1944
    @mikan1944 7 лет назад +1

    Yes! You saved the day again Khan Academy! I dunno why I can't understand my Math teacher lol.

  • @animesoulstar
    @animesoulstar 12 лет назад

    I love this man i would not be passing algebra with out him

  • @CossZt6
    @CossZt6 7 лет назад +1

    Is there any way to predict for which variable to solve first? Sometimes I need to solve complex circuits and I end up with three or four equations. However, it can sometimes be a bit difficult to choose the fastest path and trying out different paths takes some extra time, which isn't a very good thing.

  • @victoriaadolphe1013
    @victoriaadolphe1013 7 лет назад +4

    Thank the lord for kan Academy!!👍👍

  • @Stenbeck-lu2rw
    @Stenbeck-lu2rw 11 лет назад +10

    What is the software that you use? I want to be able to do this on my own computer.

    • @thedesireguardian2470
      @thedesireguardian2470 7 лет назад +3

      honestly i think this is just ms paint or something like that (yes i know this comment is 3 years old xD)

    • @goldbedvids8580
      @goldbedvids8580 3 года назад

      he says scratchpad a few times whatever that is

  • @jellie1443
    @jellie1443 8 лет назад +3

    THANK YOU!

  • @yafetteshome9515
    @yafetteshome9515 8 лет назад +1

    Ya if you add it you are right but he used subtraction that is why 5x - 15x gave him -10x but if you use addition it would give you a whole different answer so he made a mistake. I guess !!

  • @Bunniculaable
    @Bunniculaable 12 лет назад +2

    omg i forgot i had this app and i was really struggling!!

  • @therealg1478
    @therealg1478 7 лет назад +2

    You saved my life

  • @trionmeerwald3578
    @trionmeerwald3578 Год назад +1

    khan academy isnt it wrong
    dont we need to get the coefficent of y for the 2nd equation as -10 since the coefficent of y in the 1st equation is -10 i dont know if i am right just telling

    • @jonwill
      @jonwill Год назад

      If the equations were subtracted you would be correct. -10y (-) -10y = 0. But the equations were 'added'. So -10y + 10y = 0.
      .

  • @benjaminlowe5057
    @benjaminlowe5057 9 лет назад

    This was really helpful. Thankyou!

  • @ev7227
    @ev7227 5 лет назад +6

    *mAsSaGe* the equation

  • @nathanielaltman367
    @nathanielaltman367 7 лет назад +3

    It would probably be easier to find either x or y for either equation and then just plug into the other equation.

    • @sakikogookheng
      @sakikogookheng 4 года назад

      Yeah he's also covered substitution in one of the previous videos. Think he's just showing other methods

  • @AbbyAlex13
    @AbbyAlex13 13 лет назад

    thank you so much for this homework help, i think i finally get it!!!

  • @mingz83
    @mingz83 3 года назад

    Good evening, please kindly double check at 10:03 part, you said 3 X 5/4 is equal 15/4 , please correct it, it is 17/4 , by the way, thanks for great videos, I truly appreciate you.

  • @fabiososo
    @fabiososo 7 лет назад

    Thank you Khan

  • @jfg1237
    @jfg1237 10 лет назад

    THANK YOU! 😺🙏

  • @smartmike100
    @smartmike100 12 лет назад

    thank you for posting this

  • @mikeheth
    @mikeheth 14 лет назад

    @JonasM108 I did the same thing. It just so happens that in this problem, 5/4 is the answer for both x and y.

  • @neydahnajeeb1906
    @neydahnajeeb1906 Год назад

    where this 20 by 4 came from in the second last step? if thats was from addition where this 15 by 4 again came from when they were added at the top??

  • @jdhdhhdhdh6503
    @jdhdhhdhdh6503 5 лет назад

    thank you for the helpful vids

  • @sheri-san8046
    @sheri-san8046 4 года назад +1

    What do I do if both are just y and x for example, -x+y=5?

    • @nocturnalvisionmusic
      @nocturnalvisionmusic Год назад

      For this you would just multiply the entire equation by -1:
      -1 • (-x) + -1(y) = -1•5
      Which would leave:
      x-y = -5
      Then solve as usual.
      Three years later but I hope this helps anyone else :)
      Happy Thanksgiving too (11/23/23)

    • @jonwill
      @jonwill Год назад +1

      @@nocturnalvisionmusic The video is solving systems of equations with the 'elimination' method. This viewer's question would need guidance on solving with the 'substitution' method. For example: [solve for x in terms of y] yields x=y+5
      then solve for y with the new x identity [y+5+y=5] yields y=0, Now solve for x using this y value yields x = -5. So the original equation post substitutions would read: -(-5)+0=5 yielding 5=5. I too hope you had a Happy Thanksgiving!
      And please excuse the turkey on my breath. 😊

    • @nocturnalvisionmusic
      @nocturnalvisionmusic Год назад

      @@jonwill that's a good explanation! Thank you too :)
      Happy Thanksgiving 2023 to you :D

  • @Matt_Xeno
    @Matt_Xeno 2 года назад

    Bro you are my math teacher

  • @diobolic6581
    @diobolic6581 7 лет назад +1

    How would you solve this with y=4x+1 and x+y=15?

  • @TheChapinLife
    @TheChapinLife 12 лет назад

    THANKS

  • @Kagimine
    @Kagimine 14 лет назад

    Wow! This helped me so much!! Thanks for posting this~!
    ... The pretty colors helped, too. ^-^

  • @goldielemorin1471
    @goldielemorin1471 12 лет назад

    Thank you so muchhhh

  • @Slayn
    @Slayn 7 лет назад

    thank you

  • @zionfultz8495
    @zionfultz8495 2 года назад

    me watching sal solve the second equation by multiplying the top by 7 and the bottom by -5 and adding after I solved by adding the top and bottom after multiplying the top by 3/7 (I still got the right answer, but there were a lot more fractions)

  • @mightyboogster5313
    @mightyboogster5313 8 лет назад

    what do I do with equations that start with a singular y for example y=2x-3 and the other one would be y=x+4

  • @sur33no78
    @sur33no78 7 лет назад +2

    You just saved me from a 0 on my homework

  • @seanps2dude
    @seanps2dude 11 лет назад

    thats a good point. not spam

  • @JohnnyCashisone
    @JohnnyCashisone 12 лет назад +2

    Neither can mine. They need to get rid of MOST of the teachers and just use RUclips for all the classes!

  • @yafetteshome9515
    @yafetteshome9515 8 лет назад +1

    Wouldn't subtracting -10y by +10 give you a -20

  • @skurlb
    @skurlb 14 лет назад

    I understand

  • @michaelreyes29
    @michaelreyes29 8 лет назад +1

    I dont get it..

  • @seanps2dude
    @seanps2dude 11 лет назад +6

    your voice is like butter being rubbed against my ears.

  • @CCV334
    @CCV334 14 лет назад +2

    DAMN 'IT RUclips an error occurred please try again later

  • @jodikennedy4338
    @jodikennedy4338 3 года назад

    This is terribly confusing. I have some recollection of this from highschool where i was good at it and enjoyed it very much but the recollection of this does not help my understanding of it now.

  • @gamo5342
    @gamo5342 7 лет назад +1

    I stg if there r fractions on my test tomorrow somebody is gonna get hurt

  • @Maxxy03
    @Maxxy03 4 года назад

    I’m watching this during my teachers office hours rn and she being so loud and I cant hear anything wtf-

  • @veronicasmith4680
    @veronicasmith4680 7 лет назад

    I am more confused than ever. The fractions threw me off.

  • @seanps2dude
    @seanps2dude 11 лет назад

    refresh

  • @MentsAMV
    @MentsAMV 10 лет назад

    Thank You know online school doesn't mean staying up till midnight doing HW thank you I also proved my dad wrong 2! he thinks he knows it all... he only doesn't know one thing... he doesn't know all the crap in da world!!!!!

  • @Babybashog
    @Babybashog 7 лет назад +3

    none of these videos help its not just this one its everyone one them im not saying there bad but my teachers just wants us to suffer

    • @Babybashog
      @Babybashog 7 лет назад +1

      this video helps but at the same time it dose not you know what i mean

    • @Babybashog
      @Babybashog 7 лет назад +1

      sorry for going on that rant this actually help its just that i have a hard time and finals are tomorrow

  • @mggmg4446
    @mggmg4446 8 лет назад +11

    who invented this crap

    • @moongoddess3031
      @moongoddess3031 8 лет назад +11

      Let's just hope they're long gone by now because I don't need anymore of this crap in my life.

    • @thepinkshow626
      @thepinkshow626 8 лет назад +2

      Moon Goddess lol😁

    • @luhhdrey8680
      @luhhdrey8680 5 лет назад +1

      Foreal

  • @babyteen144
    @babyteen144 12 лет назад +1

    Shit*

  • @martinmaillard9032
    @martinmaillard9032 2 года назад

    salut les gens qui viennent d'euro

  • @inFamousCeRea1
    @inFamousCeRea1 11 лет назад

  • @danielkwong933
    @danielkwong933 7 лет назад

    memes

  • @FascinateMyBeing
    @FascinateMyBeing 13 лет назад

    i get it now!