Q8 (1 Viewer)

[Riviet]

Discuss.

My thoughts:
Attempted everything. It was not that hard in my opinion.

I got the x-coordinates (a and b) as (n+n^1/2)/2 but I think it's supposed to just be n+n^1/2. Anyhow, the 1/2 actually cancelled out in the next bit so I didn't realise this out till someone told me about it after the exam.

 

[zeek]

i did part a but not part b... not enough time

 

[casomerville]

I did about half of a) & b).

I also got n +- sr(n) for a & b int 8bi.

I got 0 for 8biv. Anyone else?

 

[housemouse]

Did all of a) and didnt have enough time to think about b)

 

[gamecw]

Q8
(a) (i) got it
(ii) got it
(iii) got it
(iv) didnt attempt

(5 marks)

(b) (i) this is what i wrote:
use intergration by parts to find f"(x) then solve for f"(a)=0 & f"(b)=0 rearrange n make a &b subjects..
this book i have (phoenix?) says that if u dont have time to do the question, write sumthin like that then u will still score partial marks..so i did
(ii)not attempted
(iii) not attempted
(iv)yep its 1?

 

[Bricnic]

I skipped the part where you try to work out a and b, and guessed them as (1 + 1/n ^1/2) and (1 - 1/n ^1/2). I basically just stole the stuff in ii), though I know its most likely wrong.

 

[gamecw]

Q8
(a) (i) got it
(ii) got it
(iii) got it
(iv) didnt attempt

(5 marks)

(b) (i) this is what i wrote:
use intergration by parts to find f"(x) then solve for f"(a)=0 & f"(b)=0 rearrange n make a &b subjects..
this book i have (phoenix?) says that if u dont have time to do the question, write sumthin like that then u will still score partial marks..so i did
(ii)not attempted
(iii) not attempted
(iv)yep its 1?

so i got 6 marks, 40% for this question

 

[XcarvengerX]

Write random and unfinished stuff, hoping to get the easy marks. 75% of my answers are unsatisfactory.

Part b (iv) is supposed to be 0 I think because e^-2√n will become 0 as n approaches infinity. I wrote infinity because I didn't see the small minus sign in my haste to catch up with time.

 

[pLuvia]

Didn't do finding a and b, and didn't do the part after that 6 marks gone But did the other bit.

Q8 was far too easy for a Q8 in my opinion

 

[ianc]

for b)i)

i found f'(x) and f''(x)

and then wrote some rubbish about a and b = +- √(n+n²)

do you reckon i'd get a mark for that?

 

[Riviet]

(b) (i) I pretty much should have got 4 for this, except due my silly mistake of forgetting to cross out the 2 in the denominator, I got (n + sqrt(n))/2 instead of n+sqrt(n). But I'm grateful for the 3 marks that few others got.

Basically for this 4 marker you had to find f''(x), set it to 0 and solve for x. You get a quadratic in x with coefficient(s) involving n's. Use quadratic formula and it should simplify nicely to x=n + sqrt(n).

 

[vafa]

Q8 was a nice question but not really a question as the last question in 4 unit paper. In my opinion question 8 was in the level of the question in 2005 ( i do not remember maybe it was question5) where you had to prove that integration by inducation and so on. I think the paper was easy but they could put the question about cener of an ellipse as their last question because it least it looked harder to most students than question8.

 

[silentprayer]

in the exam when i saw 8iii) i didnt even bother to look at the question cos i saw log combined with inequality... but when i was home and it just said "integrate ii)".... it appeared so obvious that iii) was the integral of ii)

also iv) too... omg... just e^