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Reply 20
slips
the p+13 was the worst bit definitely got that wrong...on the last question think it said to leave it in terms of root 2?
also on question one i got the wq/29 or whatever it was, but used my calculator to do tanh(ln2.5). was another way?


I did tanhx = sinhx/coshx = (e^2x-1)/(e^2x+1) with a bit of manipulation then sub'd the x in.

It was worth 6/7 marks that part so I thought using you're calculator would be too easy!
Reply 21
kota
Could anyone remember the marks on each questions??

For instance, 1a - 2 marks etc
1b - 7 marks


Q2 a) 3 marks, b) 5 marks
Q6 a) 2 marks, b) 6 marks
Reply 22
Adam92
I did tanhx = sinhx/coshx = (e^2x-1)/(e^2x+1) with a bit of manipulation then sub'd the x in.

It was worth 6/7 marks that part so I thought using you're calculator would be too easy!


yeah it was worth 7, but i came back to it at the end and didn't have a lot of time so just went with the calculator...i'll def get some marks for all the working before i think
Adam92
I did tanhx = sinhx/coshx = (e^2x-1)/(e^2x+1) with a bit of manipulation then sub'd the x in.

It was worth 6/7 marks that part so I thought using you're calculator would be too easy!

I just subbed 5/2 into [(e^x)-(e^-x)]/[(e^x)+(e^-x)]
Reply 24
Tomato_Soup1992
I just subbed 5/2 into [(e^x)-(e^-x)]/[(e^x)+(e^-x)]


It's all good.
Reply 25
Did anybody else get a = 128 and Q5 being 2 / root 3 ?
I got a=8 and for q5, arc length=pi/6
Also, for the last question.. How is everyone getting e^17ipi/12 ?
I just tried it again and got 77ipi/12 :|
Reply 28
SoManyFaces
I got a=8 and for q5, arc length=pi/6


At least someone got a = 8 :p: . I was convinced I was wrong not long ago but remembering back I think it is the correct answer, did you have any doubts about a = 8?
Reply 29
For question 4. b (ii) You needed to use the information in part (i) about substituting alpha into the equation resulting in 0. So if you do the same for beta and gamma you get 0 too. So all you had to do was add together f(alpha), f(beta) and f(gamma) and set it equal to 0, then the answer just dropped out and you could use the sum of the cube of the roots and what not to find a value for the sum of the squares of the roots in terms of p.
Reply 30
i got arc length = pi/6, and checked it on my calculator, so pretty sure that's right
Reply 31
SoManyFaces
Also, for the last question.. How is everyone getting e^17ipi/12 ?
I just tried it again and got 77ipi/12 :|


(1 + root3i)^8 = 2^8e^i8pi/3

(1 - i)^5 = root2^5e^-i5pi/4

Timesing the e's together gives you e^(i8pi/3 - i5pi/4) which equals e^i17pi/12
Reply 32
slips
i got arc length = pi/6, and checked it on my calculator, so pretty sure that's right


& same, pretty sure it's right.
Adam92
(1 + root3i)^8 = 2^8e^i8pi/3

(1 - i)^5 = root2^5e^-i5pi/4

Timesing the e's together gives you e^(i8pi/3 - i5pi/4) which equals e^i17pi/12


Arghhh.. I got the argument of 1-i as 3pi/4. Do you know how many marks the last q was worth?
Reply 34
SoManyFaces
Arghhh.. I got the argument of 1-i as 3pi/4. Do you know how many marks the last q was worth?


Part a) 2/3, b) 3, c) 4
Reply 35
Original post by &#946
At least someone got a = 8 :p: . I was convinced I was wrong not long ago but remembering back I think it is the correct answer, did you have any doubts about a = 8?


What question had finding an a??? ahhh
Reply 36
ALICEMOON
What question had finding an a??? ahhh



You didnt have to find a, it was question 7 which said to put in the form a root 2 e . I put 128, I made an error in earlier posts. For some reason im adamant it was 128. anyways :p:
Reply 37
Original post by &#946
You didnt have to find a, it was question 7 which said to put in the form a root 2 e . I put 128, I made an error in earlier posts. For some reason im adamant it was 128. anyways :p:


sorry to be annoying... i just wondering which part of the argand diagram you shaded? ...i shaded a little traingle type thing :s
Reply 38
Do you know how many marks question 3 was??
Reply 39
ALICEMOON
sorry to be annoying... i just wondering which part of the argand diagram you shaded? ...i shaded a little traingle type thing :s


Not annoying at all, for me I had a triangle touching the origin and the y axis.

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