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FP1.. How was it?

OP

BeitHaller

The newton raphson question got me in a tangle. I think I must have differentiated it wrong. I got 1 + 10e (^-0.5t)
that must be wrong though :frown:

Thought that paper was a toughie on the whole. Under a fair amount of time pressure

i think that is wat i differentiated it to... got the rite answer it seems 1.866?

Reply 21

Kbartlett

I know most people wont believe me but i learnt the whole book last night, after school, before that i had only done the first two chapters, and when i was looking through the book it looked quite easy, but after doing the test i think maybe i should have looked at it earilyier the test was sold.

Reply 22

mathsdave

I tapped in 1.9 for the top and the bottom of the equation, and the top number was like 20 and the bottom number 12 lol. i was probably being stupid all of a sudden though lol

Reply 23

np_desi

OP

for q4, the first part was -1 +/- 2i rite?

so e^-x (Acos2x + Bsin2x)

wasent it 4x not 2x

I got 2x

OP

BeitHaller

I got 2x

it better be or else i am screwed.. think i got minimum 50/75... was hoping for a B, but close enuf.... i guess

Reply 27

Piers

Kbartlett

wasent it 4x not 2x

2x. Remember √-4 = √4 √-1 = 2i not 4i.

I thought this test was absolutely EVIL. The differentiating I didnt even do well one of them :redface:

and the polar I got really close but not quite (I got

a²(3√3 - 2)
8

so basically I missed out a 1/2 or sumthing somewhere. most of it was OK I spose......... λ=6? for complex one.

I think the interpolation one and newton-rapsoden was okay my answers seemed sensible.

This was way harder than any past paper I attempted, including all the new set of them. BOO. Retake maybe but I really dont wanna I already have to do FP2 and 3 this july :eek:

Reply 28

k10k

6

Yeah it was i?-16/2 which is 2i which makes e^-t(Acos2t+Bsin2t)
and hence A = 1 and B=1.... I put 4t too.

Reply 29

np_desi

OP

i got

e^-t(Acos2t +Bsin2t)

we're told x = 1 and dx/dt = 1 at t=0

e^-t(Acos2t +Bsin2t) = 1

= 1(A+0) = 1

A=1

dx/dt = e^-t(-2Asin2t +2Bcos2t) + [-e^-t(Acos2t +Bsin2t)] = 1

1[0+2B] - 1[A] = 1

2B - A = 1

2B -1 = 1

2B = 2

B=1

dammmmmmmmnnnnnn i forgot that -e^-t, so i got

2B + A = 1
2B +1 = 1

2B = 0

B = 0

how many marks would i lose then? as i got the next few parts wrong too!

Reply 30

joe8232

7

I found it a really hard paper. I got A=1 and B=0 aswell. :frown:

Reply 31

futureaussiecto

13

theflcgal

ah i found it pretty much ok. been through the paper and i think i got about 67/72 so not too bad.

seeing as tought its out of 75 you'll have a bit of a problem getting that! hehe :p:

Reply 32

k10k

6

just accuracy mark isn't it your method is fine.

Reply 33

kenobi124

1

BeitHaller

I tapped in 1.9 for the top and the bottom of the equation, and the top number was like 20 and the bottom number 12 lol. i was probably being stupid all of a sudden though lol

So i'm not the only stupid one around here....
Can someone answer the question
how did you do the newton raphson?

f(x) = t + 26 - 20e^(-0.5t)

(I pressed it into the calculator a million times... so I remember it so clearly)
so... anyone able to help me?

Reply 34

mrcheese

haha, that paper screwed me!
I didn't have time to do the last 8 mark question, nor half of question 7
Thank god it doesnt count towards my offers!
Though by the sounds of this thread the first questions went alright...
for the inequality di people get something like x<0 and 2<x<4 ?

Reply 35

k10k

6

Yeah something like that.

Reply 36

np_desi

OP

kenobi124

So i'm not the only stupid one around here....
Can someone answer the question
how did you do the newton raphson?

f(x) = t + 26 - 20e^(-0.5t) - 20?

(I pressed it into the calculator a million times... so I remember it so clearly)
so... anyone able to help me?

see bold...

i screwed up on the inequalities on... i drew the graph, got x=4 and 0, but didnt know the signs, so i jus put x < 4... so some more marks lost there... as it was a 5 mark q, i guess i lost 2 for that...

Reply 37

kenobi124

1

np_desi

see bold...

i screwed up on the inequalities on... i drew the graph, got x=4 and 0, but didnt know the signs, so i jus put x < 4... so some more marks lost there... as it was a 5 mark q, i guess i lost 2 for that...

OH CRAP.... I REMEMBER NOW....
a very nasty habit of mine.... never reading the question..... dammit!
oh well.... retakes in june...

Reply 38

username22878

2

All in all, I thought it was a rather nice paper, easier than some of the past papers (7 questions instead of 8 is always nice, it seems to remove some sort of psychological barrier.. don't ask why :confused:

), and finished with about half an hour to spare. I managed to do all the 'show that' questions, of which there were a pleasing amount. I got A = 1 and B = 1, and the graph was a sinusoidal one that died to nearly zero, very quickly. The polar question was OK too, normally I have a tendancy to make silly numerical slips on these but I got to the given result first time, this time. Although that's more than can be said for the first question, in which I forgot that 1-2 ≠ 3, eventually getting to the right answer.

Reply 39

np_desi

OP

can some1 remember the marks for all the q's?

1. 5 marks
2. 5 marks
3.
4. 14 marks
5.
6.
7. 15 marks

that is wat i think.. can some1 plz post them!..thx!

FP1.. How was it?

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