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How to know when to use what rule in Differentiation?

  • 19-07-2011 8:18pm
    #1
    Registered Users, Registered Users 2 Posts: 1,506 ✭✭✭


    I'm not a beginner at Differentiation and I can usually spot when to use what rule for different equations but sometimes I just get confused and use the wrong one. I was just wondering if anyone can point me towards a useful guide on how to know when to use which rule?

    Thanks


Comments

  • Registered Users, Registered Users 2 Posts: 3,038 ✭✭✭sponsoredwalk


    Could you post a few examples of questions you're confused about along
    with your thoughts on each equation & what you see as the possibilities?
    If you do that we could tell you why possibility A, B, C & D are wrong while
    possibility E is the way to go :cool:


  • Registered Users, Registered Users 2 Posts: 5,633 ✭✭✭TheBody


    I'm guessing you are asking when to use the product, quotient and chain rule?

    For the product rule, you use it when you have two things being multiplied together...i.e a product!!

    For the quotient rule, you use it when you are dealing with a fraction type problem. (Quotient is just a fancy word for a fraction)

    For the chain rule, you use this when you have a composition of functions. What I usually say, is to use this rule when you are sure it's not a product or quotient rule problem. So, use a process of elimination.


  • Registered Users, Registered Users 2 Posts: 1,506 ✭✭✭shizz


    Sorry guys I don't really have any problems that I am stuck on I was just hoping someone might know of a place where there was a sort of guide on how to spot it. It's more so with larger equations. I think I'm getting the hag of it now though and not making the mistakes I used to.


  • Registered Users, Registered Users 2 Posts: 3,038 ✭✭✭sponsoredwalk


    It's highly likely that you're getting confused with larger equations
    because you don't know how to break it up & don't know how what
    rule can be used in what situation or why.

    Here is a list of the possibilities:

    01: Derivative of a Constant
    02: Derivative of a Constant Times a Function
    03: Derivative of a Sum
    04: Derivative of a Product
    05: Derivative of a Quotient
    06: Power Rule for Natural Powers
    07: Power Rule for Integer Powers
    08: Power Rule for Rational Powers
    09: Power Rule for Real Powers
    10: The Chain Rule
    11: Derivative of an Inverse Functions
    12: Implicit Differentiation
    13: Parametric Differentiation

    What you should notice about the list I gave is that rules 6-9 are basically
    the same rule. Here is a list of some of the special functions that come up
    along with their derivatives.

    My advice is to watch the videos on this & this website that correspond to
    the list I gave you so that you can hear someone explain what's going on
    in each situation & give you the intuition. Once you've done this you'll
    never look at "larger equations" as something scary because you will
    know how to break it all up into small chunks, each small chunk being
    solvable by one of the methods in this list.

    Once you've done this, if you want to test yourself, I personally find that
    taking the second derivative of some big implicit differentiation problem
    is the biggest thing you'll run into, try some of those problems along with
    general differentiation problems.

    I'll just point out that all you really need to worry about is the quotient
    rule & the chain rule really, everything else should be totally obvious if
    you're able to recognize what you need to do when you see an equation.


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