# Edexcel A2 C3 Mathematics 12th June 2015Watch

This discussion is closed.
3 years ago
#1241
(Original post by adorablegirl1202)
Thanks I got the first one in the end! Now for 4b if I understand correctly we sub it in and then you're saying we get -1 and since it's mod we make it 1. But if we were to work out f(x) then we find two values???
f(-1) is always 2mod(-1) + 3 = 2 + 3 = 5.
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3 years ago
#1242
(Original post by MATTTT)
Can some on help. Normally to find the range you have to draw the graph. However this question is 3 marks and they differentiate it and get x=2.

Is there a way that you can differentiate the function and find the range ?
If the curve has a maximum/minimum, then you can differentiate to find dy/dx, at a max/min dy/dx = 0, so you can use this to find the range
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3 years ago
#1243

Can someone please help me with part b? Really stuck
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3 years ago
#1244
Hi could someone help me with this question please
the first part was Prove that
1-tan^2tetha / 1+tan^2tetha = cos 2tetha

I understood this bit but I don't understand the next bit:
Hence, or otherwise, provetan^2π/8 = 3 – 2√2.
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3 years ago
#1245
Why is point C (π-α ,0) when surely it should be (2π-α ,0)? (Elmwood B).

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3 years ago
#1246
(Original post by anonwinner)
If the curve has a maximum/minimum, then you can differentiate to find dy/dx, at a max/min dy/dx = 0, so you can use this to find the range

oh i see. But how would you know that curve has a max/ minimum?
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3 years ago
#1247
(Original post by MATTTT)
oh i see. But how would you know that curve has a max/ minimum?
Well you should know what the basic graphs look like. x^2 graphs have a max/min because of their U shapes, so do x^3 graphs
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3 years ago
#1248
What's the hardest C3 paper and/or hardest trig "show that" question?
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3 years ago
#1249
do we reckon its going to be like the 2013 one tomorrow
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3 years ago
#1250
(Original post by MATTTT)
oh i see. But how would you know that curve has a max/ minimum?
Well if you really had no other way of finding out, d^2y/dx^2 < 0 for maximum and >0 for minimum.. But differentiating twice can sometimes be hard. If you're not given an equation, kinda just have to figure it out using general idea of the graph..
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3 years ago
#1251
(Original post by Jimmy_M)
What's the hardest C3 paper and/or hardest trig "show that" question?
prove that Sin(9+10) = 21
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3 years ago
#1252
(Original post by 11234)
do we reckon its going to be like the 2013 one tomorrow
Wouldn't mind that really, as long as nothing like Q8 comes up.. Could do without that stress tbh
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3 years ago
#1253
(Original post by hajs)
Why did you square both sides? Does squaring get rid of the mod?
yes it does
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3 years ago
#1254
(Original post by Jimmy_M)
Wouldn't mind that really, as long as nothing like Q8 comes up.. Could do without that stress tbh
Other than the final question and the question about g(x) and g^-1(x), none of the other questions were hard on that paper
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3 years ago
#1255
(Original post by Ripper Phoenix)
yes it does
Thanks for that tip about squaring for mod questions, I always mess those up
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3 years ago
#1256
(Original post by BioAgent)
For the domain and range sometimes the mark scheme doesn't include x/f(x) is equal to all real numbers. I f you do include it do you loose marks?
You will never loose marks for giving more information then they ask for, ALWAYS write the domain and range and that they belong to the real numbers just in case there is a mark for it
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3 years ago
#1257
(Original post by Ripper Phoenix)
yes it does
Oh really. I didnt know lol. So if you had to draw say f(x)= 2|x| +3 do you square it or ..?
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3 years ago
#1258
Can someone tell me if we have to memorize cosec, sec & cot graphs? Struggling to learn these
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3 years ago
#1259
https://07a69ccf283966549a9350d1a669...%20Edexcel.pdf

For 10c, I got to the stage 1/sinx - 3cosx = 0 not sure where to go from there???
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3 years ago
#1260
(Original post by theoeht)
What other information was given in the question
LOL sorry i was joking, don't try working it out because it doesn't exist lol. Never seen the vine?

https://www.youtube.com/watch?v=t97R3jxbl6E
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