Turn on thread page Beta
    Offline

    3
    ReputationRep:
    Well, this is TSR... we're emosh about maths
    Offline

    15
    ReputationRep:
    (Original post by TeeEm)
    I am sure brittanna knows that, but I am sure he did that for the sake of simplicity, given the OP did not understand why e^ln3 = 3
    The difference is though is what that brittanna said is mathematically incorrect. What I said is not
    Offline

    14
    ReputationRep:
    Read the above posts for intuition. In a nutshell what you need to know is: e^ln(x) = x
    ln(e^x) = x
    Plug in x=3.
    Offline

    19
    ReputationRep:
    (Original post by ubisoft)
    Ah fair enough. Can you explain how what the other user said about ln is incorrect? That's how I still think about it too, would like to know if it's wrong.
    it does not harm to think powers that is exactly how I have taught it to the huge majority of students.

    however ex = exp(x)

    for inverse functions

    f-1f(x) = ff-1(x) =x (identity function)

    by analogy

    exp(lnx) = x for all positive x, which we write elnx =x
    ln(exp(x) = x for all x, which we write ln(ex) =x
    Offline

    19
    ReputationRep:
    (Original post by B_9710)
    The difference is though is what that brittanna said is mathematically incorrect. What I said is not
    I am sorry I hurt your feelings ...
    He was incorrect and you were a tiny bit incorrect.

    But for both of you I said....
    From a teaching point of view, both of you are "correct"

    I have often made deliberate decisions to teach mathematical facts incorrectly (to some weak students). This is done to avoid confusion with a "heavy duty" mathematically correct but confusing explanation.
    Offline

    19
    ReputationRep:
    (Original post by thecatwithnohat)
    who even knew drama could arise in the maths forum...about maths :lol:
    I do not know how I manage it ....
    Every time I get involved into a debate it ends up in an argument ...
    There was one last April it lasted over a week, during which 2 people got banned ...
    It was me versus someone else which I do not wish to name in the maths courses forum... then you get your supporters fighting with you and the other person's supporters fighting ... I left after 2 days but the fight went on for about a week
    Offline

    14
    ReputationRep:
    (Original post by TeeEm)
    I am sorry I hurt your feelings ...
    He was incorrect and you were a tiny bit incorrect.

    But for both of you I said....
    From a teaching point of view, both of you are "correct"

    I have often made deliberate decisions to teach mathematical facts incorrectly (to some weak students). This is done to avoid confusion with a "heavy duty" mathematically correct but confusing explanation.
    Did you teach A-level TeeEm?
    Offline

    15
    ReputationRep:
    (Original post by thecatwithnohat)
    who even knew drama could arise in the maths forum...about maths :lol:
    I know
    Offline

    19
    ReputationRep:
    (Original post by stochasticking)
    Did you teach A-level TeeEm?
    I only teach a bit from this year because I retired

    I teach GCSE, A level exc Decision and high end stats and undergrad methods

    (only privately of course)
    Offline

    15
    ReputationRep:
    (Original post by TeeEm)
    it does not harm to think powers that is exactly how I have taught it to the huge majority of students.

    however ex = exp(x)

    for inverse functions

    f-1f(x) = ff-1(x) =x (identity function)

    by analogy

    exp(lnx) = x for all positive x, which we write elnx =x
    ln(exp(x) = x for all x, which we write ln(ex) =x
    No one is saying that is wrong. But why give that as an answer when someone just wants a simple explanation. You have to try and make it intuitive really don't you.
    Offline

    14
    ReputationRep:
    (Original post by TeeEm)
    I only teach a bit from this year because I retired

    I teach GCSE, A level exc Decision and high end stats and undergrad methods

    (only privately of course)
    Oh sweet. For undergrad methods, do you teach partials, matrix algebra etc?
    Offline

    19
    ReputationRep:
    (Original post by B_9710)
    No one is saying that is wrong. But why give that as an answer when someone just wants a simple explanation. You have to try and make it intuitive really don't you.
    That is exactly what I said not to you but to the chap that correctly or incorrectly called the rest "smug" and your comment sensible.

    Maybe it came out the wrong way and your "name" got punished as a result ... I merely said mathematically that is incorrect however from a teaching point of view correct.
    I would have given the same explanation like you to a student here...
    Many people before you, also said the same as you.
    I was annoyed not with your explanation but with that guy's comment calling the rest of us "smug"
    scroll back to the start and see for yourself
    Offline

    19
    ReputationRep:
    (Original post by stochasticking)
    Oh sweet. For undergrad methods, do you teach partials, matrix algebra etc?
    topics such as those in this index thread
    http://www.thestudentroom.co.uk/show....php?t=3330283

    My site has a lot more questions
    Offline

    15
    ReputationRep:
    (Original post by TeeEm)
    That is exactly what I said not to you but to the chap that correctly or incorrectly called the rest "smug" and your comment sensible.

    Maybe it came out the wrong way and your "name" got punished as a result ... I merely said mathematically that is incorrect however from a teaching point of view correct.
    I would have given the same explanation like you to a student here...
    Many people before you, also said the same as you.
    I was annoyed not with your explanation but with that guy's comment calling the rest of us "smug"
    scroll back to the start and see for yourself
    Fair enough then. I wouldn't get annoyed about it though, it's only people on TSR
    Offline

    14
    ReputationRep:
    (Original post by TeeEm)
    topics such as those in this index thread
    http://www.thestudentroom.co.uk/show....php?t=3330283

    My site has a lot more questions
    Cheers!
    • Study Helper
    Offline

    16
    ReputationRep:
    Study Helper
    (Original post by ubisoft)
    Ah fair enough. Can you explain how what the other user said about ln is incorrect? That's how I still think about it too, would like to know if it's wrong.
    I'm sure TeeEm will correct me if I'm wrong but I don't think he was criticising the actual mathematics posted - I think the was criticising the fact that the other poster thought he'd come up with some new way of presenting the argument when in fact all he was doing was saying the same thing as everyone else but in different words!

    There are only so many different ways you can say "the definition of an inverse function is one that reverses the effect of the original function"
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: September 21, 2015

University open days

  1. University of Bradford
    University-wide Postgraduate
    Wed, 25 Jul '18
  2. University of Buckingham
    Psychology Taster Tutorial Undergraduate
    Wed, 25 Jul '18
  3. Bournemouth University
    Clearing Campus Visit Undergraduate
    Wed, 1 Aug '18
Poll
How are you feeling in the run-up to Results Day 2018?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.