Could they ever ask you to differentiate/integrate....

If they gave question stating something like:

$y= \frac{3x^{3}-1}{x-2}$

"Find dy/dx."

How would I solve this. I don't know how I would put this into index form without fractions first.

This is in case it comes in a C2 or even a C1 paper.

Thanks

Reply 1

davros

16

Original post by wrestlingfan55

If they gave question stating something like:

$y= \frac{3x^{3}-1}{x-2}$

"Find dy/dx."

How would I solve this. I don't know how I would put this into index form without fractions first.

This is in case it comes in a C2 or even a C1 paper.

Thanks

do you cover the quotient rule or product rule in your core modules?

Reply 2

SpiggyTopes

14

I pretty sure that would only be asked in C3/4.

Reply 3

wrestlingfan55

OP

Original post by davros

do you cover the quotient rule or product rule in your core modules?

Err nope.

I only know that if you have two fractions to add you find the LCM and cross multiply for the numerator (but that's GCSE Maths). But this one is just a single fraction, so I have no idea how I'd tackle this sort of question.

Reply 4

davros

16

Original post by wrestlingfan55

Err nope.

I only know that if you have two fractions to add you find the LCM and cross multiply for the numerator (but that's GCSE Maths). But this one is just a single fraction, so I have no idea how I'd tackle this sort of question.

In that case you're probably "safe" from this sort of question!

If you're interested, google "product rule" or "quotient rule" or get hold of a decent A level book that covers these rules - they're not too difficult to learn :smile:

Reply 5

natninja

21

you could express it as a product of (3xcubed-1) x (x-2)^(-1) and do it that way for differentiation (which means it could well come up in C2 exams), integration-wise at least C4 most likely FP3. (assuming you are taking Edexcel)

Original post by davros

In that case you're probably "safe" from this sort of question!

No probably about it.

Original post by wrestlingfan55

If they gave question stating something like:

$y= \frac{3x^{3}-1}{x-2}$

"Find dy/dx."

How would I solve this. I don't know how I would put this into index form without fractions first.

This is in case it comes in a C2 or even a C1 paper.

Thanks

This is not a C1 or C2 skill so you will not be asked anything like this.

Reply 8

davros

16

Original post by Mr M

No probably about it.

Pah! I can't be doing with this modular nonsense - why can't people just learn Maths like they used to :biggrin:

Original post by davros

Pah! I can't be doing with this modular nonsense - why can't people just learn Maths like they used to :biggrin:

Well they will soon!

Reply 10

Ateo

9

Original post by natninja

you could express it as a product of (3xcubed-1) x (x-2)^(-1) and do it that way for differentiation (which means it could well come up in C2 exams), integration-wise at least C4 most likely FP3. (assuming you are taking Edexcel)

That still requires knowledge of the product rule.

Reply 11

Ynang

1

If you're doing OCR Maths (I don't know about MEI) then unless there's a way to cancel that down to a single line, you would only ever be asked it in core 3 or 4

Reply 12

Ateo

9

You may be asked to do this if the numerator is divisible by the denominator, so that you get a polynomial which you can differentiate. In the case you gave there is a remainder when you divide the numerator by the denominator and your expression will contain a term which you will not be able to differentiate yet.

Reply 13

uberteknik

21

Differentiation: use either quotient rule: u/v = (v.du/dx - u.dv/dx)/v²
or convert to product: (3x³-1)(x-2)^-1and use product rule:
u.v = u.dv/dx + v.du/dx

If it was an integration question then the numeratoir is of higher order than the denominator so must be converted to a partial fraction first before integrating.

Could they ever ask you to differentiate/integrate....

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