c2 proof help please!

Hey, i was wondering if anyone knew what proofs we are supposed to learn for ccea as c2? The specification wasn't very clear!

In CCEA you need to know

The top one you definitely need to know.
I've heard the bottom one can be asked.

The two that Richard has given are the only ones you need to learn a proof for.

Thanks

The two that Richard has given are the only ones you need to learn a proof for.

Doesn't the spec say you need the log proofs as well as the trig proofs?

You only need to know two trig identities and the rules of logs. I don't entirely understand what you mean by "log proofs".

If Edexcel then learn the "Sum of" formula

Yes I know, but do you not need to know how to prove these identities and rules?

Well I wouldn't consider that there is a proof for log rules. They are simply derived from rules of indices. The two identities are easy to prove. The specification says that only knowledge and use of them is required. Nothing about a proof.

Did you make that mistake?


-Putch =)

Yes, essentially a proof. I honestly wasn't sure whether we specifically had to know how to derive them or not, but thanks for clearing that up! Need to read the spec for myself instead of the one my school 'made' ha.

I really apologise for this. Question 8 on today's paper went a bit beyond the spec. I got the log proof wrong. I have given the link for the spec if you want to have a look (page 22.) It mentions the rule but not that its proof is required. Turns out like another repeat is heading my way. I deserve many offensive words for telling you that it wasn't needed. I apologise again. Also if you want the proof here it is:

http://www.rapidtables.com/math/algebra/logarithm/Logarithm_Base_Change.htm

http://www.rewardinglearning.org.uk/qualifications/Results.aspx?g=1&t=1&c=r&s=62&dt=0&v=0&f=0&q=28&d=d

Not a problem my man, I knew it anyway! I knew they'd throw something like that our way.

Bad paper? It was definitely the hardest C2 I've done. Convinced I only lost 2 marks though!

Did you get area = 2 for question 6 that required you to integrate? And I agree that paper was hard. I finished in 1 hour 10 mins and sat 20 mins trying to figure out that proof with no luck.

Yep I did, I was integrating with respect to y and had y^(-0.5). I did the paper twice then sat and did a few of them over again due to my sense of self worry haha. Hope the scaling is generous though.

Were your limits -1 and -4 or 4 and 1? I did -1 and -4 and my function was -y^(-0.5) so I got a negative area but then said that it equals 2.