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    (Original post by jayshah31)
    \text{Chain rule} > \text{Quotient rule}

    \displaystyle (\cos 2x)^{-1}
    There's no point using solely the chain rule for the sake of it... in this case, it makes little difference in terms of the number of steps involved, but in many cases using the chain rule is just creating work for yourself. The reason why the quotient rule often cuts out steps is because the quotient rule is derived from the chain rule, so you cut out that derivation.

    That is, if u and v are functions of x, then:
    \newline \dfrac{\mbox{d}}{\mbox{d}x} \left( \dfrac{u}{v} \right) = \dfrac{\mbox{d}}{\mbox{d}x} \left( uv^{-1} \right)\newline

= \dfrac{u'}{v} - \dfrac{u}{v^2}\times v'\newline

= \dfrac{u'v - uv'}{v^2}

    Often you end up repeating this whole kaboodle for the sake of not just using the quotient rule. And this post went on for way longer than I intended it to :p: Sorry about that.

    (Original post by Adam92)
    Don't judge me here, I've been self-teaching this module so I don't have a full understanding yet, but what's wrong with writing \dfrac{1}{\cos 2x} as (cos2x)^-1? Then using the chain rule to differentiate?
    Nothing wrong with doing that; they're both just different paths to the same thing. If you wanted you could even write it as \sqrt{1 + \tan^2 2x} and differentiate from there :p: I self-taught C2-4, M1 and FP3 so I understand where you're coming from.
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    (Original post by nuodai)
    Nothing wrong with doing that; they're both just different paths to the same thing. If you wanted you could even write it as \sqrt{1 + \tan^2 2x} and differentiate from there :p: I self-taught C2-4, M1 and FP3 so I understand where you're coming from.
    I think I'll stick to the easy way thanks :p:

    :sigh: I have to do S1, M1, C3-4, and maybe even FP2-3. I win
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    (Original post by Adam92)
    YES please.
    no
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    (Original post by maxfire)
    no
    :curious:
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    Your mother and I can. In bed. Whilst listening to Stravinsky.
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    Stravinsky?

    brother please
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    (Original post by Glutamic Acid)
    Your mother and I can. In bed. Whilst listening to Stravinsky.
    My mothers dead.
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    (Original post by Glutamic Acid)
    Your mother and I can. In bed. Whilst listening to Stravinsky.
    Must you lower the tone? :hmmm:
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    (Original post by Glutamic Acid)
    Your mother and I can. In bed. Whilst listening to Stravinsky.
    Oh good, that free's up daddy for some welding out back.
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    I cannnnn!!! but I really can't be bothered....
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    (Original post by jayshah31)
    Seems you drifted away a little on the last line there :p:
    Sec(x) and the c and x are right next to each other - almost as if the creator of the keyboard (and the inventor of sec and unknown x) all wanted mathematicians to make such mistakes in the future :p:
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    (Original post by jayshah31)
    Seems you drifted away a little on the last line there :p:
    :rofl:

    And they say maths only makes me h0rny...:rolleyes: :p:
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    Sorry, I was inebriated. I still am, just less so.
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    (Original post by Adam92)
    My mothers dead.
    That would explain the lack of movement last night.

    :ninja:

    edit: Leave a ******* name on the comment, coward.
 
 
 
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