Change of base formula | Logarithms | Algebra II | Khan Academy

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  • Опубликовано: 3 окт 2024

Комментарии • 100

  • @amywelsh2582
    @amywelsh2582 3 года назад +17

    Dear Sal Khan, My name is Amy Dewe-Mathews. I'm 45 years old and I'm back in school for Nursing. By trade I'm a hairdresser, which I've done for the last 28 years of my life. After my divorce, 5 years ago, I knew I needed a change, let alone a challenge! My passion has always been to make people feel better....... so Nursing was a given. While earning my degree, I had to take intermediate Algebra. I couldn't pass to save my life! I dropped out and started working in a salon again. Then, a friend recommended I transfer to a different SchooL. So, I enquired and before I knew it I was enrolled and taking classes. OMG!!!!! I saw that here, I would not only have to take Intermediate Algebra, but College Algebra!!!! ARE YOU KIDDING ME?????!!!!!!! I knew it was over before it began. Then You Entered MY Life!!!! Not only did I receive a B in Intermediate Algebra, I'm On my way to getting a B in college Algebra. What Khan Academy has done for me is monumental. But here's the kicker! Forget about the fact that I can now fulfill my dream.......... I was watching CBS This Morning just now and as soon as I heard that voice I sat up and starting crying. It was so beautiful for me to put a face to the voice I've been hearing for the last 4 months. You helped me pass these courses and I NEED you to know what you're doing is not only detrimental but so caring valuable. I know I couldn't have passed these courses without you and I want to say Thank You. You're compassion is sorely needed in this world, esp. now.

    • @middleofdecember9862
      @middleofdecember9862 6 месяцев назад +2

      interesting story, thanks for sharing and good luck with your nursing job

  • @sunkissedtortoise999
    @sunkissedtortoise999 2 года назад +11

    I love how he doesnt just show how to do it, but he shows why it works. This helps me understand so much better! At 6:37 my mind was b l o w n

  • @aurorabtwCS
    @aurorabtwCS 6 лет назад +26

    use macro keys to change colours quickly, and will be able to stay faithful to colours fast.

  • @SteveLPDNB
    @SteveLPDNB 7 лет назад +41

    I like the was you say "C'th power" - Say it really angrily then you can seethingly seeth the word "C'th"

    • @saimamostafiz8125
      @saimamostafiz8125 6 лет назад

      OMG!! Why doesnt this comment have more likes???? XD

    • @pianoforte17xx48
      @pianoforte17xx48 3 года назад +1

      @@saimamostafiz8125 because we are nerds

  • @MsPaigeKat
    @MsPaigeKat 11 лет назад +4

    This is great; thank you so much. I have a test today, and was feeling totally unprepared because my teacher ran out of time and had to rush through this entire lesson in about 5 minutes. Now I know what's going on, though. Thanks!

  • @פרופסוראור
    @פרופסוראור 9 лет назад +62

    And..... you're doing it again!!
    simplifying all the calculus material and somehow making it all clear! I can't thank you enough for your help :)

  • @talhahasan8365
    @talhahasan8365 11 лет назад +7

    Brilliantly explained Sir, I definitely owe you one.
    (Well actually I owe you many)

  • @strawberry.teacake
    @strawberry.teacake 6 месяцев назад

    Thank you so much. This really helped me prepare for my math test as I have a bad teacher and no one else to properly explain things to me. I am so grateful for your videos :)

  • @sotash
    @sotash 12 лет назад +2

    I love the calculator graphic!!! VERY helpful!!!

  • @nikhiltripathi3012
    @nikhiltripathi3012 8 лет назад +9

    Sal is epic!! nd the derivation is awesome

  • @nozzerjuice
    @nozzerjuice 7 лет назад +12

    you should be the narrator on shows about the universe.

  • @PedroHenrique-vs3mf
    @PedroHenrique-vs3mf 6 месяцев назад

    Really helpful! Will remember you

  • @JohnnyMontilla
    @JohnnyMontilla Год назад +1

    THANKS! THIS HELPED!

  • @saltydustx
    @saltydustx 8 лет назад +3

    Perfect explanation tyvm :)

  • @LoiteringReaper
    @LoiteringReaper Год назад

    Be careful with parentheses around the "a" value, exponent can be within and outside. If the parentheses are surrounding log(a) like (log(a)) or [log(a)]^x then the entire log is raised to the power of x.

  • @denissemitchell9891
    @denissemitchell9891 7 лет назад +4

    great video! gosh thank you thank you thank YOU! I can sense the passion between you and mathematics. This is why we should follow our passions... the energy spreads.

  • @lexinaut
    @lexinaut 10 лет назад +1

    Nice and clear! And now a base logarithm joke. "Great Scott! Napier was an exponent of logarithms!" John Napier, a Scottish fellow, logged in with a book explaining logarithms in 1614. Logarithms speeded up various calculations done by hand greatly, thus speeding up mathematical and scientific progress. Logarithms are empowering even if sometimes it seems like they are glowering! Time to log out!

  • @flaviodelcid8088
    @flaviodelcid8088 7 лет назад +20

    Who else heard the fly ? 😂😂

  • @bradjkirwan
    @bradjkirwan 13 лет назад +7

    Good job Sal, just in time for my Math exam next week :)

    • @bradjkirwan
      @bradjkirwan 4 года назад +5

      @Uros Durdevic Seems like I was less of a procrastinator 8 years ago!

  • @TroutSniffer69
    @TroutSniffer69 7 лет назад +1

    You can change the base using that calculator. Use parentheses, and a comma to separate the base. such as log (x+2),4. or even approx ((log ((x+2),(5))÷log ((x-3),(2))). Most scientific calculators I have used for logs, have this funtion.

  • @jerrymahone335
    @jerrymahone335 6 лет назад +1

    go to Change of Base Formula for Logarithms. -9/14 log base 2 (9/14) -5/14 log base 2 (5/14) = .94 you would never get this answer using this procedure. if learning trees is in your future go to Change of Base Formula for Logarithms NOW! then go to Decision Tree 4: Information Gain.

  • @elijah_3473
    @elijah_3473 4 года назад +5

    I don’t know what I would do without you in my life 😩

  • @nightskiesburialground5886
    @nightskiesburialground5886 7 лет назад +2

    Thanks! I have a test today and this helped to refresh my understanding.

  • @BrownBoy1911
    @BrownBoy1911 12 лет назад +1

    i f**king love you man! so helpful on the night before the exam when you just realised you forgot logs.....

  • @abdulazezalshammari9399
    @abdulazezalshammari9399 4 года назад +1

    Thanks for making youtube great and useful 👌🏼

  • @2010chickenbutt
    @2010chickenbutt 12 лет назад

    @Shadowriku40 very true very true

  • @ngndnd
    @ngndnd 3 года назад

    What is up with all the extra steps. You could have easily explained this in under a minute. All this other useless info makes it confusing, literally all you need to do is divide and thats it.

  • @lucapoli9602
    @lucapoli9602 8 месяцев назад

    But if you have a F calculator why in the world would you use this method

  • @paramchauhan9972
    @paramchauhan9972 9 месяцев назад

    But sir what if base is larger than Which we done of logarithm

  • @omarmahli8311
    @omarmahli8311 6 лет назад +1

    I like when he change the colors 😂

  • @skoolwifi3835
    @skoolwifi3835 6 лет назад

    I come here when my online class can't explain it, which is log9037424729 whatever % of the time

  • @johnathanhimka
    @johnathanhimka 6 лет назад +1

    cth power

  • @alicialexists
    @alicialexists 2 года назад

    Thank you so much. I never understood the change of base formula until I saw this video.

  • @zhipengchen4622
    @zhipengchen4622 3 года назад

    Jeez I was suffering in Math30 and found this treasure clear and straightforward

  • @aninditakundu928
    @aninditakundu928 2 года назад

    This channel made my change of base rule for logarithm much much clear

  • @janaesadventures1405
    @janaesadventures1405 4 года назад

    How do you do log10 (1/2)t/1.5=log10 0.2

  • @avsec9742
    @avsec9742 4 года назад

    Thank you kind sir, you have released me from frustration.

  • @gfujigo
    @gfujigo 3 года назад

    Awesome!!! Pure awesomeness!

  • @zainnadeem5023
    @zainnadeem5023 Год назад

    GIVE THIS MAN HIS COLORS

  • @marioperez5804
    @marioperez5804 6 лет назад +3

    Great video man, helping me for tomorrow's exam. 😊

    • @hamzaperfect1395
      @hamzaperfect1395 2 года назад +1

      how was the exam...3 years ago

    • @marioperez5804
      @marioperez5804 2 года назад +1

      @@hamzaperfect1395 Got a 7 in Maths in that course I think xD. But it could had been easilly a 5 xD

    • @hamzaperfect1395
      @hamzaperfect1395 2 года назад +1

      @@marioperez5804 I don't know what marking system you are using..but it sounds great..awesome! I am in grade 10 right now

    • @marioperez5804
      @marioperez5804 2 года назад

      @@hamzaperfect1395 Yeah, it is! Good luck, bro! ✊

    • @hamzaperfect1395
      @hamzaperfect1395 2 года назад +1

      @@marioperez5804 Thank you..What do you do now btw..I am at the point of life where i need to choose between engineering and medical..so i ask everybody what they do and how they like it:)

  • @arshadmuhammad6879
    @arshadmuhammad6879 4 года назад

    the colours really make it much more easier to understand :)

  • @WaCKafAce
    @WaCKafAce 13 лет назад

    @WaCKafAce Also, this helped me understand this so much better :)

  • @bunnii0321
    @bunnii0321 3 года назад

    I love every time my professor posts a Khan academy video and I hear this voice! Speaks so clear and I love when he repeats his steps!

  • @Leuel48Fan
    @Leuel48Fan 7 лет назад +3

    "Most calculators only allow log(10) and ln".... not true unless you're using outdated software/hardware. TI-84 with OS 2.55 (MathPrint update) has logBASE function under Math and scroll up twice. Pretty useless formula nowadays as the answer will still require a calculator irregardless, and if you're using one, simply make sure to have an updated one!

    • @dareal2669
      @dareal2669 7 лет назад +5

      Leuel48Fan u might stfu this video was around 6 years ago

    • @Leuel48Fan
      @Leuel48Fan 7 лет назад

      No, you might want stfu because MathPrint was available since 2010. Most teachers taught outdated methods (Source: was an algebra student).

    • @dareal2669
      @dareal2669 7 лет назад +4

      Leuel48Fan so that doesnt justify my point it wasnt that much known as today

    • @brookeh9358
      @brookeh9358 6 лет назад +3

      well, truth, but some people cant afford advanced calculators, and cant use computers or internet/phone stuff on tests, so this is like, necessary. especially since knowing how to do it is a question on the test :)

    • @ElizabethAlmey
      @ElizabethAlmey 6 лет назад +2

      This is an old video! But actually alot of universities don't allow that level of calculator on tests so it is kinda helpful, at least for me :)

  • @seediamarong
    @seediamarong Год назад

    Thank u bro❤

  • @WaCKafAce
    @WaCKafAce 13 лет назад

    @Shadowriku40 Thanks :) Sorry for being a... noob.

  • @atishmistry6959
    @atishmistry6959 4 года назад

    thank you

  • @water6133
    @water6133 3 года назад

    Thanks

  • @barathkumar5478
    @barathkumar5478 6 лет назад

    how to change the base root(10) to root (10) in log

  • @emmadaniel5533
    @emmadaniel5533 4 года назад

    Thank you so much! so helpful

  • @johnathanhimka
    @johnathanhimka 6 лет назад

    anyone else hear squeeky fart noises?

  • @madalixful
    @madalixful 4 года назад

    So helpful, wow thanks a lot

  • @jcers
    @jcers 4 года назад

    Thanks Sal

  • @etheReal6780
    @etheReal6780 6 лет назад +1

    Did “Ayy to the seeth power... Ayy to the seeth power” bother anyone else?

  • @jhumabarik7174
    @jhumabarik7174 6 лет назад

    Doing bad

  • @sophiawang7654
    @sophiawang7654 6 лет назад

    why did you make the base 10 at 2:07?? can someone explain?

    • @rockyk6805
      @rockyk6805 6 лет назад

      Because log of 10 is equal to just log.
      every log has a base of 10
      just like every exponent is raised to the power of 1 Ex: 5^1 = 5

  • @skylargoddard2661
    @skylargoddard2661 6 лет назад +2

    I hate math, I give up.

  • @AmeenRabea
    @AmeenRabea 7 лет назад

    I really love mathematics
    😍❤
    But really don't know when & where are we going to use this in the real life!!
    Since I graduated from computer engineer collage until now I never used it (at least the Logarithm) and I don't think that I'm going to use it until I teach it to my son when he take it in the school!
    What is the real life application of Log that will be used in daily weekly bases?

    • @MoesFingers
      @MoesFingers 7 лет назад +3

      Salam. Logs are useful when trying to evaluate to what power you need to raise a given number to reach a different specific number. In your experience of programming it may not be useful, but in all honesty that depends on what you are coding. In certain software applications, the reverse of an exponent can be particularly useful if you have a function such as log to evaluate.

    • @pottingmix3733
      @pottingmix3733 7 лет назад +1

      binary search tree

    • @frede1905
      @frede1905 7 лет назад +1

      You don't need certain pieces of mathematics in real life, but it's a beautiful art that makes some people, like me, happy.

  • @tilakgupta131
    @tilakgupta131 6 лет назад

    Awesome explanation

  • @mphobogopa3239
    @mphobogopa3239 8 лет назад

    coool

  • @tahmenaferdous5213
    @tahmenaferdous5213 7 лет назад

    In the first equation, why did u make the base 10?

    • @phoenixfeather487
      @phoenixfeather487 7 лет назад

      Tahmena Ferdous if the base is not specified then it is defaulted to 10, like in the way when you try and find the cube root the number in front of the thing is a three but when nothing is there there is actually a two there

  • @bobbyit5238
    @bobbyit5238 8 лет назад

    He is smart but his voice puts me to sleep

  • @barathkumar5478
    @barathkumar5478 6 лет назад

    logbase10(10^1/3)=2/3

  • @blazeinvince
    @blazeinvince 7 лет назад

    Where did he get the 10 from? I know that the default is 10 but x could have been any number couldn't it?

    • @hero_16-f1w
      @hero_16-f1w 7 лет назад +1

      Hung-Tam Yie yes it can be any number

    • @hero_16-f1w
      @hero_16-f1w 7 лет назад

      Hung-Tam Yie Ten is the standard base to use in logarithmics that’s why he used it.

  • @WaCKafAce
    @WaCKafAce 13 лет назад

    What do you use to write/draw and record?

  • @loganbmoy
    @loganbmoy 8 лет назад

    Hi

    • @loganbmoy
      @loganbmoy 8 лет назад

      Khan nice explanation as always

  • @YungA80
    @YungA80 12 лет назад

    Log base 2 to the power 9

  • @jyothi26rab
    @jyothi26rab 6 лет назад

    please show us how to calculate without using calculator thanks

  • @MoHaMmEdxALNaTsHe
    @MoHaMmEdxALNaTsHe 8 лет назад

  • @neilsucks
    @neilsucks 11 лет назад

    wow, that IS what makes me feel good.

  • @wclin5310
    @wclin5310 5 лет назад

    wanna know what grads in us when u had to learn this subjects?