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Edexcel C3 - 12.06.06 - The 'how did it go' thread!

Reply 220

bigbadb1319

can any1 get hold of the paper?? n then we can post sum answers....

Reply 221

andreasms

14

um guys?
It kinda said that K>1.

So I found 0.5 my self in the beginning and tried to work out a number greater than 1.
I guess then 1.5 is the answer

Reply 222

Sollytear

gayyyyy

For the temperature last bit your supposed to say:
As t tends to infinity "t --> [infinity]", e^-0.05t tends to 0 ("e^-0.05t --> 0), therefore, T --> 400(0) + 25 = 25.

T will never reach 20

i got 1/2k too

Rabite

I think that's right.

They were talking about the third? Second? part though, where you have to find fg(0.25k) or something.

fg(x)= ln ( [2x+k] + k)
fg(k/4)= ln (3k/2)
That's what i got at least, hope it helps

Reply 225

sebbie

15

definitely harder than the other two..... i got the iteration wrong, kept putting it into y= and wondering why it was wrong, of course i've now realised it was dy/dx...

there was a lot of stuff in there that wasn't immediately obvious and required some amount of thought...

did others get -3root7/8 at one point and 135 degrees as the only answer at another?

Reply 226

bigbadb1319

k u know 4 question 5, when we had to find out x1 x2..etc, did we have to put it in radians, i think ma cal was in deg. do u rekon i'd get any marks?

Reply 227

Twiglet

OP

2

PS. argh ****. "instead of turning point" i wrote "root". penis weed.

oh poooo, I did the same!
I thought the paper was harder than the last 2, and different from all the solomon papers - there seemed to be a lot of emphasis on graph sketching. So annoying with the sin2A, I was sitting there thinking that I could have done that 2 years ago, but the whole obtuse angle thing stumped me.. I managed a couple of lines of working though and got something bizzarre like -root (63/64) as the answer - but just got that thru putting it all in the claculator....wonder if theyll give me any marks, cos it is right!.... shame I havent learnt C4 yet !!

xxx

Reply 228

3.14159265

13

i found this paper MUCH harder than the two past ones. C4 has to be good
was the rate question -1.64

i left it as -1.64 and didnt write it decreases at a rate of 1.64 per minute

will i lose a mark? i believe i may have lost a comfortable 15 marks on the paper.

Reply 229

Warren_Sullivan

sebbie

definitely harder than the other two..... i got the iteration wrong, kept putting it into y= and wondering why it was wrong, of course i've now realised it was dy/dx...

there was a lot of stuff in there that wasn't immediately obvious and required some amount of thought...

did others get -3root7/8 at one point and 135 degrees as the only answer at another?

I agree with the 135 degree angle question, however I got (+3root7)/8, as sin was also positive in the domain given with the cos value. Therefore 2sin@cos@ is also positive

Reply 230

Warren_Sullivan

3.14159265

i found this paper MUCH harder than the two past ones. C4 has to be good
was the rate question -1.64

i left it as -1.64 and didnt write it decreases at a rate of 1.64 per minute

will i lose a mark? i believe i may have lost a comfortable 15 marks on the paper.

So long as you indicated the temperature decreased at this rate, the question asked you to give the answer in terms of degrees C/min, so unless you did that and put -1.64 degrees C/min I'm guessing you'd lose probably just one mark for incorrect sign

Reply 231

Dougy_S

1

reakon i lost a good 25 marks :mad:

, really wasnt a great paper. First 4 questions were ok, then managed to do bits of the rest, just fell to piecestowards the end :confused:

Reply 232

andreasms

14

Let's just hope the boundaries are lowering lol.
That's our only hope. Well my only hope :biggrin:

Reply 233

sebbie

15

Warren_Sullivan

I agree with the 135 degree angle question, however I got (+3root7)/8, as sin was also positive in the domain given with the cos value. Therefore 2sin@cos@ is also positive

A was between 270 and 360

therefore 2A between 540 and 720

sin is negative in that range....

Reply 234

spacko101

Warren_Sullivan

I agree with the 135 degree angle question, however I got (+3root7)/8, as sin was also positive in the domain given with the cos value. Therefore 2sin@cos@ is also positive

however sin was not positive becuase it was the 4th quadrant.

Reply 235

firestone

9

franks

oh poooo, I did the same!

Yeah I did that too, argh. But hopefully it won't matter since it's f'(x) - the gradient that's changing sign - so it would be a root since the gradient is 0 at the turning point...well hopefully anyway.

Reply 236

theoneandonly

1

for the 1.64 aswer, i wrote
(-) cm gap then 1.64

will they still knock of a mark for it?

Reply 237

Revelation

1

r3m0t

Duh, if T >= 25, then T >= 20. THey probably did it because they thought that in other papers, people looked at the answer and worked backwards.

I interpreted the question wrong. It said why cant T reach 20, I was like "hmm thats obv you cant evaluate ln(negative)" but then I thought WHY didnt they say why cant T<25. I thought it was trying to catch me out. Luckily I just put T=20, you got ln(negative) showed you cant evaluate ln(negative) and just left it at that.

Reply 238

Warren_Sullivan

cos @= 3/4
therefore, by drawing a right angled triangle...
sin @= (root7)/4 (also positive)
sin2@= 2sin@cos@= 2.(root7).1/4.3.1/4= (3root7)/8
?

Reply 239

Pure T

1

That was a joke, it was soooooo hard. My trig isnt up ot scratch and the only part of that I know is when u have the R involved. That didnt come up! GRRRR. I will be happy with a D lol. ( ps was hoping for C or B)

Edexcel C3 - 12.06.06 - The 'how did it go' thread!

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