What do u think u got? (1 Viewer)

What do u think u got?


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emo-kid-91 said:
discussion among my classmates afterwards revealed 10a - integrating a log - wasn't something we're taught in 2u.
correct based on my own experiences.
 

lyounamu

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I am not sure. But I think I did very well. Enough discussion from me as it is a bad luck talking about the exam...
 

minijumbuk

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Solutions to 10a)

y = ln (x-2)

ey = x - 2
x = ey + 2

A = 7ln 5 -∫ln 50(ey + 2)dy
= 7ln 5 - [ey + 2y]ln 50
= 7ln 5 - [eln 5 + 2ln 5 - e0 - 2(0)]
= 7ln 5 - 5 - 2ln 5 + 1
= 5ln 5 - 4
 

jozza80

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minijumbuk said:
Solutions to 10a)

y = ln (x-2)

ey = x - 2
x = ey + 2

A = 7ln 5 -∫ln 50(ey + 2)dy
= 7ln 5 - [ey + 2y]ln 50
= 7ln 5 - [eln 5 + 2ln 5 - e0 - 2(0)]
= 7ln 5 - 5 - 2ln 5 + 1
= 5ln 5 - 4
Thats what I got!

COOOOLLL!!!!

:)
 

minijumbuk

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METHOD 2: (The way I did it)

d/dx (x-2)ln (x-2)
= (x-2)/(x-2) + ln (x-2)
= ln (x-2) +1

Therefore ∫ (ln (x-2) +1)dx = (x-2)ln (x-2)
73 ln (x-2) dx = [(x-2)ln (x-2)]73 - ∫73dx
= 5ln5 - 3ln 1 - [x]73
= 5ln 5 - 7 + 3
= 5ln 5 - 4
 

anonomis

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emo-kid-91 said:
discussion among my classmates afterwards revealed 10a - integrating a log - wasn't something we're taught in 2u.
in 2u u r not ment to know how to integrate a log but u can still do that question. u have to first find the area of the rectangle, which was 7ln5 as
L=7 and h=5,
therefore area = 7ln5.
Then you had to make the function as x in terms of y,
x = e^y +2
and then integrate that function. then you had to subtract your answer from the area of the rectangle
= 7ln5 - (4 + 2ln5)
= 5ln5 - 4
 
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Alex499 said:
I'll be lucky to pass.
DAMN that was the worst test ever.
And I sure as hell never learnt to integrate logs. I just left it the same and integrated it with the hope that I might get a sympathy mark
ha me too, with the whole integrating a log thing. i know exactly what i had to do, my friend told me as soon as we got outside, and i was just like, dammit. i left out 15 marks... i just hope i get in the 80s ha.
 

kangms

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OHHhhh FARK FARK FARK..for question 10a. I think i divided 7 by 2. EXAM PRESSURE damn it!!!! Eh..only 1 mark off for that. Felt like SHIT after the exam...
 

Rix123

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emo-kid-91 said:
discussion among my classmates afterwards revealed 10a - integrating a log - wasn't something we're taught in 2u.
yeah but you didnt have to - u had to make x the subject and use the y axis so that you integrated sumthing like e^Y...not integration of logs
 

Rix123

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sorry just realised someone already said it :p
 

dance2urownbeat

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minijumbuk said:
Solutions to 10a)

y = ln (x-2)

ey = x - 2
x = ey + 2

A = 7ln 5 -∫ln 50(ey + 2)dy
= 7ln 5 - [ey + 2y]ln 50
= 7ln 5 - [eln 5 + 2ln 5 - e0 - 2(0)]
= 7ln 5 - 5 - 2ln 5 + 1
= 5ln 5 - 4
that is so simple now.
i integrated logx as logx! win! haha. oh well. i think i did pretty well except for that.
 

K8i454

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sad face is all i can say...
i hate series application and maxima/minima problems are not my friend.
everytime i went to find area i tried to use fucking solid of revolution.
i want to cry.
god help me in three unit.
im considering writing not attempted on every booklet.:angry:
 

SkimDawg

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Around 100 - 110. Maybe a low band 6 if im lucky
 

pookins

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I think I got around 118

BUT I know i made a mistake in 10b, I accidently left out a ^2 on the L, and therefore my answer was sqrt(L/2) instead of L/sqrt2.

As it was a mistake, and when you look at it you can see i've left out the ^2, do you think I could still get a mark for that? because I know at my school they have this way of marking, that if you make a small error, and not something you obviously don't know, they don't penalise you for it... kind of like a transcription error...

The question was out of 3, do you know how many marks i could get? I did everything else right in the question, just that error... =(
 

tybermon j

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Why does everyone talk about Q10 a...

WHY DIDN"T I MINUS THAT STUPID SQAURE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

0 marks for stupidity.
 

Timothy.Siu

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pookins said:
I think I got around 118

BUT I know i made a mistake in 10b, I accidently left out a ^2 on the L, and therefore my answer was sqrt(L/2) instead of L/sqrt2.

As it was a mistake, and when you look at it you can see i've left out the ^2, do you think I could still get a mark for that? because I know at my school they have this way of marking, that if you make a small error, and not something you obviously don't know, they don't penalise you for it... kind of like a transcription error...

The question was out of 3, do you know how many marks i could get? I did everything else right in the question, just that error... =(
heeey, i did exactly the same mistake but when i checked it i found it...but yeah u shud get marks just maybe 1 off
 

obah

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minijumbuk said:
METHOD 2: (The way I did it)

d/dx (x-2)ln (x-2)
= (x-2)/(x-2) + ln (x-2)
= ln (x-2) +1

Therefore ∫ (ln (x-2) +1)dx = (x-2)ln (x-2)
73 ln (x-2) dx = [(x-2)ln (x-2)]73 - ∫73dx
= 5ln5 - 3ln 1 - [x]73
= 5ln 5 - 7 + 3
= 5ln 5 - 4
This is what i did. :)

100-105/120 for me i think
 

pookins

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I thought i got it right, and was really confident, so I didn't check it and checked the other questions instead... Stupid silly mistakes =(
 

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