How do you differentiate y^2=4ax ? (1 Viewer)

enigma_1

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Thanks

Btw do you need implicit differentiation? Because I haven't learnt that.
Another method is appreciated.
 

Drongoski

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Use implicit differentiation.

 
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Alternatively

 
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anomalousdecay

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If you are only doing 3-unit, you don't need implicit differentiation.

Btw, I'm not sure if you are allowed to use it in the HSC exams unless its the ext.2 paper. Not sure on this though. Can someone clarify?
 
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If you are only doing 3-unit, you don't need implicit differentiation.

Btw, I'm not sure if you are allowed to use it in the HSC exams unless its the ext.2 paper. Not sure on this though. Can someone clarify?
You can use any valid HSC method in any paper - the thing is - you will never need to. E.g. integration by parts of y = lnx when you can use the inverse function (x = lny and integrate wrt y)
 

braintic

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If you are only doing 3-unit, you don't need implicit differentiation.

Btw, I'm not sure if you are allowed to use it in the HSC exams unless its the ext.2 paper. Not sure on this though. Can someone clarify?
Implicit differentiation is an extremely useful tool in Extension 1. It mightn't be required, but I believe any Ext 1 teacher who doesn't teach it is depriving their students.

I'm thinking specifically of the related rates questions where (for example) a ladder is sliding down a wall, in fact anything that would otherwise require Pythagoras.
 
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Sometimes when you end up with an expression in the form

one should remember that one need not implicitly differentiate or take a square root when attempting to find stationary points of D(x). This is because and when this is set to zero we get which can be obtained from

(related but not completely - but I think Braintic you were hinting at this?)
 

rumbleroar

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Another way of doing it is splitting it off into two cases by square rooting y^2. Although this method is lengthier, it doesn't require implicit :)
 
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You can do that but perhaps need some inverse function motivation...
 

enigma_1

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Thanks everyone! Does anyone know if we're allowed to use implicit differentiation in an extension one paper?
 

rumbleroar

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Thanks everyone! Does anyone know if we're allowed to use implicit differentiation in an extension one paper?
My tutor said you are allowed to use Ext 2 methods in Ext 1 (in this case, implicit differentiation), but it is generally frowned upon and if you get the method wrong, you get the entire question wrong because you aren't specifically using methods taught in ext 1. So just be careful with using ext 2 methods and skills in ext 1 :)
 

studybuddy101

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Yeah +1 to above post. That's what my teacher would tell me. Besides, the paper generally steers you into a certain method anyways so there isn't a considerable disadvantage not knowing implicit for ext1
 

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