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# STEP Formulae/ Identities Tweet

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IMPORTANT: You must wait until midnight (morning exams)/4.30AM (afternoon exams) to discuss Edexcel exams and until 1pm/6pm the following day for STEP and IB exams. Please read before posting, including for rules for practical and oral exams. 28-04-2013
1. STEP Formulae/ Identities
I was just wondering what formulae and identities you need to remember (aren't given in formulae booklet) for STEP (1, 2 AND 3).

This is because I was doing a question that involved using the identity for the difference of two cubes which I hadn't come across. So are there any other identities like this that you need to know about?
2. Re: STEP Formulae/ Identities
(Original post by brittanna)
I was just wondering what formulae and identities you need to remember (aren't given in formulae booklet) for STEP (1, 2 AND 3).

This is because I was doing a question that involved using the identity for the difference of two cubes which I hadn't come across. So are there any other identities like this that you need to know about?
Which identity are you referring to?

3. Re: STEP Formulae/ Identities
(Original post by raheem94)
Which identity are you referring to?

Yeah.

I haven't finished A level maths yet, but it doesn't seem like something you would learn in C3 or C4.
4. Re: STEP Formulae/ Identities
If you like that one, you'll also like its companion...

Last edited by Stray; 15-06-2012 at 00:07. Reason: DUH - too late at night
5. Re: STEP Formulae/ Identities
(Original post by brittanna)
Yeah.

I haven't finished A level maths yet, but it doesn't seem like something you would learn in C3 or C4.
It isn't in C3/C4 but i learned this in year 8 so it is probably an extremely common identity.
6. Re: STEP Formulae/ Identities
(Original post by SubAtomic)
How is that true
Its a typo, it should have been,
7. Re: STEP Formulae/ Identities
(Original post by raheem94)
Its a typo, it should have been,
Funny typo considering p and q are at opposite ends of a keyboard.
8. Re: STEP Formulae/ Identities
I had only ever learned the difference of two squares. What other 'extremely common identities' are there that I need to know about that are quite often needed to answer questions?
9. Re: STEP Formulae/ Identities
(Original post by SubAtomic)
How is that true
Good point... I had mistyped it. Sorry 'bout that. Yes - not so much a typo as a brain-fail.
Last edited by Stray; 15-06-2012 at 00:08.
10. Re: STEP Formulae/ Identities
(Original post by SubAtomic)
Funny typo considering p and q are at opposite ends of a keyboard.
lol

(Original post by brittanna)
I had only ever learned the difference of two squares. What other 'extremely common identities' are there that I need to know about that are quite often needed to answer questions?
I just said extremely common because it was year 8 stuff.

I don't know which ones you are expected to know.
11. Re: STEP Formulae/ Identities
(Original post by brittanna)
Yeah.

I haven't finished A level maths yet, but it doesn't seem like something you would learn in C3 or C4.
I wouldn't really call it an identity, so much as something you can just spot. If you know the factor theorem (pretty sure this is early A level), it's easy to come up with also.
12. Re: STEP Formulae/ Identities
(Original post by Slumpy)
I wouldn't really call it an identity, so much as something you can just spot. If you know the factor theorem (pretty sure this is early A level), it's easy to come up with also.
Yep, seen these cubics and some other various equations just before a section on roots, polynomials and factors/factorisation on a pdf, will cut and paste a bit(no I wont I will have to tex it because it won't bloody accept the paste in tex).

13. Re: STEP Formulae/ Identities
(Original post by brittanna)
I was just wondering what formulae and identities you need to remember (aren't given in formulae booklet) for STEP (1, 2 AND 3).

This is because I was doing a question that involved using the identity for the difference of two cubes which I hadn't come across. So are there any other identities like this that you need to know about?
It's worth knowing the general solutions to:

sin(x) = sin(y)

and the cos and tan equivalents.

The formula book does contain the identities for things like:

cosAcosB = ...

but it's worth being aware of them as they are often not explicitly taught.
14. Re: STEP Formulae/ Identities

You'd be surprised how often these come up.
15. Re: STEP Formulae/ Identities
Don't know if anything I am posting is of any use as I aren't doing STEP. So correct me or ignore me

Here is another equation I have been introduced to today.

And some stuff about using exact forms of to verify properties of

For instance

Last edited by SubAtomic; 15-06-2012 at 17:33.