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Official Edexcel C3 Discussion Thread watch

1. (Original post by john1234567)
i'm not sure i agree with that. if cot2x = 0 then you should be able to put x=45 in and get 0
(Original post by MrBo)
I got the same first 2 solutions as this, but for the last ones i'm not too sure. Dosn't cotx have asymtotes every 90 plus/minus 180? So if this is true 2x can't equal either 45 or 135
There's another way then:

That's equal to

Thus you get

and now that is definitely and

Don't worry about it....like hardly any one got it so the grade boundaries would probably take off at least 2 marks to accommodate the loss
2. (Original post by john1234567)
just a few questions i remember

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this is the one with the minimum (a,b) and you have to find a and b, did anyone get the same as me?

so a = -0.196

then put x = -0.196 into the original equation to find b = 0.812

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graph of y = ln(|x|) was pretty simple, i checked on wolframalpha, got it right
mate i think you got the 1/cosx wrong you can't use product rule here because it is constant/function and so need to use chain rule by taking the reciprocal of cosx
3. The exam was pretty easy, so easy that I ended up making some really silly mistakes, I think I forgot to put ln on both sides for the last question when taking logs to both sides. and I totally ****** up question one by not looking at it correctly, that's 4 marks gone.
4. (Original post by milliondollarcorpse)
I don't know how to differentiate arcsinx, lucky I still managed to do it anyway
actually i meant arctanx. and the question got us to do just that

(Original post by Remarqable M)
mate i think you got the 1/cosx wrong you can't use product rule here because it is constant/function and so need to use chain rule by taking the reciprocal of cosx
both ways work, i've tried it
5. How On Earth Did I Get 1 Wrong!
6. (Original post by Arsey)
Very hard I thought. Here are my solutions
haha i got every differentiation alright, but thing is for the x=tany differentiation i laid down two workings using different method to check if i get the same answeer
will i get mark???
7. In the graph for ln(mod(x)) if I have drawn only one part of the graph how many marks would i lose out of 3
8. That went so bad... i couldn't do most of the paper ... i am now dreading the results day
9. (Original post by alithegreat)
In the graph for ln(mod(x)) if I have drawn only one part of the graph how many marks would i lose out of 3
probably 2. coz one mark for the real ln, one mark for the mirrored and i think 1 mark for the asymptote bit
10. How did everyone find this exam.I just want to know if the general opinion was that it was hard or easy. I found the test quite hard...similar to c2 last june.
11. I really hope the grade bondaries are low...I made so many silly mistakes
12. Ye it was a tough exam like C2 ... just hope the boundaries are low ...
13. my mates who did it found it real easy.. but thats only cuz they had a friend from another school who finished the same exams half an hour earlier who gave them the questions!
14. (Original post by hammerhasni5)
my mates who did it found it real easy.. but thats only cuz they had a friend from another school who finished the same exams half an hour earlier who gave them the questions!
how unfair . I made so many silly mistakes in my exam, i'm just hoping the grade boundaries are low-like they were for C2. However some people found the exam easier than C2, so you never know.
15. Pretty easy

Got 97% worst case scenario
16. we all have different answers for number 8 and Q9 last part
17. (Original post by Arsey)
of course, so 45 and 135 will also work.
wait a minute. it wont because if u put 45 or 135 back in the equation

cosec^2x- cot 2x u dont get one. its maths error!! so it dont work

u cant have 1/ tan 90 because tan 90 is an asemtope
18. (Original post by crazygirl29)
wait a minute. it wont because if u put 45 or 135 back in the equation

cosec^2x- cot 2x u dont get one. its maths error!! so it dont work
dont use the calculator. try it on paper and treat the math errors as 1/0

i think it does work
19. why is everyone so quite???
20. That was ****. Everyone in my class found it hard but all you guys found it so easy. Can't believe I got R = 6 for one of the questions....epic fail.
I think my lowest is going to be 65/75. 1 word...............RETAKE!

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