What do u think u got? (1 Viewer)

[cardinalsfan70]

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]

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]

Solutions to 10a)

y = ln (x-2)

e^y = x - 2
x = e^y + 2

A = 7ln 5 -∫^{ln 5}₀(e^y + 2)dy
= 7ln 5 - [e^y + 2y]^{ln 5}₀
= 7ln 5 - [e^{ln 5} + 2ln 5 - e⁰ - 2(0)]
= 7ln 5 - 5 - 2ln 5 + 1
= 5ln 5 - 4

 

[o0-Prodigy-0o]

i shink i went alright hopefully band 6

 

[jozza80]

Solutions to 10a)

y = ln (x-2)

e^y = x - 2
x = e^y + 2

A = 7ln 5 -∫^{ln 5}₀(e^y + 2)dy
= 7ln 5 - [e^y + 2y]^{ln 5}₀
= 7ln 5 - [e^{ln 5} + 2ln 5 - e⁰ - 2(0)]
= 7ln 5 - 5 - 2ln 5 + 1
= 5ln 5 - 4

Thats what I got!

COOOOLLL!!!!

 

[minijumbuk]

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]

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

 

[mynamewastaken]

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]

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]

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]

sorry just realised someone already said it

 

[dance2urownbeat]

Solutions to 10a)

y = ln (x-2)

e^y = x - 2
x = e^y + 2

A = 7ln 5 -∫^{ln 5}₀(e^y + 2)dy
= 7ln 5 - [e^y + 2y]^{ln 5}₀
= 7ln 5 - [e^{ln 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]

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]

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

 

[pookins]

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... =(

 

[henry08]

75-84, perhaps better.

 

[tybermon j]

Why does everyone talk about Q10 a...

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

0 marks for stupidity.

 

[Timothy.Siu]

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]

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]

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 =(