Higher Level Maths 2009(Paper 1): How was it for you?

ayapatrick · 05-06-2009 1:59pm

kevogy wrote: »

question 7 c part i
how do you u show root is between 2 and 3?

i got dy/dx

solved the quadratic
got x = 1

f(x) = such and such
put f(2) and f(3) in and it changes sign. you will get a neg answer and a positive thus the root lies between them!

QueenOfLeon · 05-06-2009 2:00pm

In the distance/speed differentiation part, did anyone end up with a really stupid looking differential? After subbing in the t i think mine was something like root 26 over 5......

xOxSinéadxOx · 05-06-2009 2:00pm

^ OPPPPSSS

did people get x/y for the implicit function one?

Amirani · 05-06-2009 2:00pm

Do you get marks for writing the Newton Raphson and/or differentiating the function?

ayapatrick · 05-06-2009 2:01pm

Piste wrote: »

You find f(2) and f(3) and if the sign changes between them the root lies between them.

oh goody what i done:D

kevogy · 05-06-2009 2:01pm

xOxSinéadxOx wrote: »

newton raphson

ahhh ****er

xOxSinéadxOx · 05-06-2009 2:02pm

Anne-Marie!! wrote: »

In the distance/speed differentiation part, did anyone end up with a really stupid looking differential? After subbing in the t i think mine was something like root 26 over 5......

YEP. I got 5/root 26 I think

ayapatrick · 05-06-2009 2:02pm

xOxSinéadxOx wrote: »

^ OPPPPSSS

did people get x/y for the implicit function one?

i think that what i got. i left it as2x/2y though!

Amirani · 05-06-2009 2:02pm

xOxSinéadxOx wrote: »

^ OPPPPSSS

did people get x/y for the implicit function one?

Yeah I think so.

BLARG · 05-06-2009 2:02pm

ayapatrick wrote: »

oh goody what i done:D

Haha yeah. I just got a minus and a positive and just said "therefore lies between___"... sneaky guess.

xOxSinéadxOx · 05-06-2009 2:03pm

kevogy wrote: »

ahhh ****er

I think I was wrong actually :pac:

ayapatrick · 05-06-2009 2:03pm

kevogy wrote: »

ahhh ****er

not the way!
look at my post above this !

kevogy · 05-06-2009 2:03pm

Anne-Marie!! wrote: »

In the distance/speed differentiation part, did anyone end up with a really stupid looking differential? After subbing in the t i think mine was something like root 26 over 5......

i think i got 5 over root 26 meters per second

QueenOfLeon · 05-06-2009 2:06pm

kevogy wrote: »

i think i got 5 over root 26 meters per second

O wait, ya, thats what i got. Then i multiplied them both by root 26 to make it look nicer so got 5xroot26 over 26

OxfordComma · 05-06-2009 2:07pm

Yeah, I got 5/root 26 m/s... I was certain it was wrong but it kept coming out like that!

OxfordComma · 05-06-2009 2:09pm

Oh yeah, what did ye get for the tangent to the curve in 7(b)? I got something with 4's and 9's in it...can't remember. I got either 3/4 or 4/3 for the slope, not sure which!

05-06-2009 2:11pm

That was grand!
It think I dropped 10-20 marks on the paper. It was pretty much as expected, and the standard of questions was low enough.

They did make the 2nd diff. one a bit wordy, though. Anne and Barry have no life :P

QueenOfLeon · 05-06-2009 2:12pm

niallsparky wrote: »

Do you get marks for writing the Newton Raphson and/or differentiating the function?

Last night on 2fm he said theres a certain amount of marks for writing a formula and more for filling it in.

xOxSinéadxOx wrote: »

^ OPPPPSSS

did people get x/y for the implicit function one?

Yups

.:FuZion:. · 05-06-2009 2:13pm

1fahy4 wrote: »

Oh yeah, what did ye get for the tangent to the curve in 7(b)? I got something with 4's and 9's in it...can't remember. I got either 3/4 or 4/3 for the slope, not sure which!

I got 1/2 for the slope.... :rolleyes:

Elli-May · 05-06-2009 2:13pm

timmywex wrote: »

I diff'd the formula and got somthing over (x-3)^2

Then i said since a square will be positive, its not possible to get a negative slope, thus its not possible to have m1.m2=-1

ohhh yeah that'd make a lot of sense lol
I ended up subbing in 2 x values and then finding out what they were equal to and putting it back into the original formula and got something like -2=0 which obviously cant be right so they cant be perpendicular. Hope you can do it that way too

05-06-2009 2:15pm

Elli-May wrote: »

ohhh yeah that'd make a lot of sense lol
I ended up subbing in 2 x values and then finding out what they were equal to and putting it back into the original formula and got something like -2=0 which obviously cant be right so they cant be perpendicular. Hope you can do it that way too

Yup. That way works (:

xOxSinéadxOx · 05-06-2009 2:15pm

what's the newton raphson formula? I may have done it wrong

is it X1 = Xo -f(Xo)/f'(Xo)

cos that's what I did mmmm

05-06-2009 2:17pm

xOxSinéadxOx wrote: »

what's the newton raphson formula? I may have done it wrong
is it X1 = Xo -f(Xo)/f'(Xo)

cos that's what I did mmmm

That's the one. I just messed around until I got a good answer. Couldn't remember the formula!

.:FuZion:. wrote: »

I got 1/2 for the slope.... :rolleyes:

I got 2 I think

whadabouchasir · 05-06-2009 2:24pm

Elli-May wrote: »

I ended up subbing in 2 x values and then finding out what they were equal to and putting it back into the original formula and got something like -2=0 which obviously cant be right so they cant be perpendicular. Hope you can do it that way too

We were always told not to sub values in to prove something,as if you do,you only prove that this is true for the two x values that you used rather than for all tangents.

JW91 · 05-06-2009 2:24pm

You know for question 7(c) part (ii) when it said that you had to show that the root was less than 2.5.

a lot of you said that you sub in 2.5 but should you not sub in a number that's less than 2.5? since it says that you have to prove its LESS than 2.5

I subbed in 2.49 but i wrote down that i was subbing it in as it was less than 2.5 so would i still be okay even if they did mean you to sub in 2.5?

Pygmalion · 05-06-2009 2:25pm

I answered 7 questions with plenty of time left, most things SEEMED to work out, except for 2 or 3 part Cs which I think I got mostly right, but I guess I can't really be sure.

1 part A I got 9/6 (hopefully they won't mind I didn't simplify).
1 Part B(i) worked out
1 Part B(ii) I got 1<x<2
1 Part C I got something like c = (sqrt(6)/2)*b + 1.

2 Part A I got x=-2, y = 6 I think
2 Part B(i): F(x) has unreal roots; g(x) has real, equal roots; h(x) has real roots(unequal)
2 Part B(ii): can't remember off the top of my head.
2 Part C(i) I got something like (n(q^2))/(p^2+2np+n^2)
2 Part C(ii) I can't remember exactly but I got 2 values for q, I think 0 and 1, but I remember thinking I was doing it very weirdly, and would have expected it to be in terms of r.

Skipped 3, don't like it.

4 Part A I got -2 I think.
4 Part B(i) worked out.
4 Part B(ii) I got 1 + 1/3 - 1/n - 1/n+2 or something, second term in there might've been + or -, 1/3 or 1/2, can't be bothered doing it again or worrying over it, whichever answer I get I'll be convinced I got the opposite in the exam.
4 Part B(iii) 2/3 I think (again, this depends on above answer)
4 Part C(i) I got a(r^2m) or a(r^2m-1).
4 Part C(ii) I got a(r^m) or a(r^m+1).
4 Part C(iii) worked out.

Can't remember 5 Part A but I checked it at the time and it worked out.
5 Part B worked out :P
5 part C I got 2 and 4.5 or something, I got two answers each for X and Y but then said that log of negative is undefined so crossed those out.

6 Part A I got (6x-1)*(cos(3x^2 - x))
6 part B(i) I got it to work after some scribbling on opposite page :P.
6 part B(ii) I got t^3 + t for the speed and 130m/s at 5 seconds.
6 Part C(i) asymptotes were x = 3 and y = 0
6 Part C(ii) I said that derivative (worked it out) was always negative, therefore slopes at no points can be perpendicular.

7 Part A I got dy/dx = x/y (or y/x, can't remember)
7 Part B(i) I got 4t/(t^2 - 2) (maybe the t on top wasn't there, can't remember)
7 Part B(ii) I got something like 4x +/- y +/- 9 = 0
7 Part C seemed to all work out handy enough. For part (i) get f(2) and f(3) and since one is negative and one positive it must cross X-axis between them.
Part C(ii) is same, but with f(2) and f(2.5)
Part C(iii) get next approx. values for each, they're both > 2.5 but Barry's is smaller, therefore it's closer.

8 Part A: 3x^2 + 3x - 1/x + c
8 Part B(i) was 1/2 I think.
8 Part B(ii) was like 12+2/3 or something close.
8 Part C I did it and seemed to get 2/3(pi)(r^2)h, then I just went back and multiplied everything by a half.... Attempt marks for me hopefully :P.

.:FuZion:. · 05-06-2009 2:25pm

Deleted User wrote: »

I got 2 I think

Bollox I did it again and got 4/3 lol.

xOxSinéadxOx · 05-06-2009 2:27pm

so did everybody think that anne and barry thing was just misleading? I was just like WUT?

OxfordComma · 05-06-2009 2:27pm

JW91 wrote: »

You know for question 7(c) part (ii) when it said that you had to show that the root was less than 2.5.

a lot of you said that you sub in 2.5 but should you not sub in a number that's less than 2.5? since it says that you have to prove its LESS than 2.5

I subbed in 2.49 but i wrote down that i was subbing it in as it was less than 2.5 so would i still be okay even if they did mean you to sub in 2.5?

The question already told you that the root was between 2 and 3, so it was asking you to prove that it was also between 2 and 2.5. Don't worry tho, it was a very badly phrased question. They can't really award more than 5 marks for it, and they'lll give you 2 or 3 attempt marks for anything!

05-06-2009 2:29pm

.:FuZion:. wrote: »

Bollox I did it again and got 4/3 lol.

Oh noes!
I did every question so I should be Ok if I got it wrong anyway

Yeah, I thought that question was misleading, Sinead. The maths was fine, but the English didn't really help. Probably more confusing than anything else.

Higher Level Maths 2009(Paper 1): How was it for you?

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