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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: hifer on November 05, 2007, 01:04:56 pm

Title: Exam 1 Graphs & Relations Answers
Post by: hifer on November 05, 2007, 01:04:56 pm
My answers..
1. D
2. C
3. E
4. B
5. D
6. E
7. C
8. B
9. A
Title: Exam 1 Graphs & Relations Answers
Post by: reg on November 05, 2007, 01:21:12 pm
Graphs and relations Q9.

Objective function: Z = 2x + ky, maximum occurs only at (100, 0).

Hence

200 = 2x + ky
y = (200 - 2x) / k

Function exists at both (100, 0) and (50, 50), this can only be true when k = B = 2 (not k = 1, A).

Unless I'm horribly wrong :(.
Title: Exam 1 Graphs & Relations Answers
Post by: SilverBullet on November 05, 2007, 01:23:24 pm
got 4 or five right which is not a bad result for myself
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 01:26:24 pm
Quote from: "reg"
Graphs and relations Q9.

Objective function: Z = 2x + ky, maximum occurs only at (100, 0).

Hence

200 = 2x + ky
y = (200 - 2x) / k

Function exists at both (100, 0) and (50, 50), this can only be true when k = B = 2 (not k = 1, A).

Unless I'm horribly wrong :(.


Lol I got B for Qn 9 as well ... worked it out differently though :P
Title: Exam 1 Graphs & Relations Answers
Post by: hifer on November 05, 2007, 01:27:35 pm
Quote from: "reg"
Graphs and relations Q9.

Objective function: Z = 2x + ky, maximum occurs only at (100, 0).

Hence

200 = 2x + ky
y = (200 - 2x) / k

Function exists at both (100, 0) and (50, 50), this can only be true when k = B = 2 (not k = 1, A).

Unless I'm horribly wrong :(.


umm, if K = 2, at  (50,50) Z also = 200

Which means there 2 maximums, which can't be true...
Title: Exam 1 Graphs & Relations Answers
Post by: reg on November 05, 2007, 01:29:34 pm
Haha maybe, I was under the impression the function had to go through (50, 50). Apparently not. Somebody else input plz :p

on second though you are right.

scratch that, i have no idea anymore. thanks :@
Title: Exam 1 Graphs & Relations Answers
Post by: Defiler on November 05, 2007, 01:30:14 pm
Same except for 7, which I got B.
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 01:48:17 pm
Damn, I originally had A for Qn9, why didn't I leave that answer!!! grr
Title: Exam 1 Graphs & Relations Answers
Post by: gulamali on November 05, 2007, 02:09:41 pm
Quote from: "Defiler"
Same except for 7, which I got B.


how did you get B ... i got E for this question, knowing me I'm probably wrong ;[
Title: Exam 1 Graphs & Relations Answers
Post by: Defiler on November 05, 2007, 02:11:49 pm
Okay, what I did was...

y = x^3

y = 1, x = 3

hence

1 = 3^3

therefore

y=(1/27)x^3

if we are going to x...

y=cubert(1/27)x^3

y=(1/3)x

sub in (3,1)

1=1

I would of picked E if I assumed (1/27) was a constant.

But it appears that I've done it wrong.
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 02:12:35 pm
Quote from: "gulamali"
Quote from: "Defiler"
Same except for 7, which I got B.


how did you get B ... i got E for this question, knowing me I'm probably wrong ;[


I got E too...but it's wrong i think
Title: Exam 1 Graphs & Relations Answers
Post by: Nick on November 05, 2007, 02:13:31 pm
Quote from: "Odette"
Quote from: "gulamali"
Quote from: "Defiler"
Same except for 7, which I got B.


how did you get B ... i got E for this question, knowing me I'm probably wrong ;[


I got E too...but it's wrong i think



I got E aswell.
Title: Exam 1 Graphs & Relations Answers
Post by: dxb on November 05, 2007, 02:25:30 pm
Quote from: "Nick"
Quote from: "Odette"
Quote from: "gulamali"
Quote from: "Defiler"
Same except for 7, which I got B.


how did you get B ... i got E for this question, knowing me I'm probably wrong ;[


I got E too...but it's wrong i think



I got E aswell.



Got E too

I'm pretty sure its wrong, because the graph represents a x3 transformation already, so to undo this, you would have to square root it and not cube it again.

Meh, I've got no idea.
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 02:34:15 pm
Wow the 4 of us got E... hmm
Title: Exam 1 Graphs & Relations Answers
Post by: Nick on November 05, 2007, 02:38:11 pm
Can someone explain to me how it can't be E?
Title: Exam 1 Graphs & Relations Answers
Post by: millstone on November 05, 2007, 02:48:17 pm
can someone please explain why 7 is C?
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 02:57:09 pm
Quote from: "Nick"
Can someone explain to me how it can't be E?


Oh i know... :shock:...surprisingly I know something :shock:
You need to use the formula y=m * x^3 + c  => m= rise/run= 1/3
Therefore you get y= (1/3)x^3, making C the correct answer
Using the points in Option C (1, 1/3), you get the right answer ...
If you want me to explain it further just let me know
Title: Exam 1 Graphs & Relations Answers
Post by: Mystery on November 05, 2007, 03:03:24 pm
Quote from: "Odette"
Quote from: "Nick"
Can someone explain to me how it can't be E?


Oh i know... :shock:...surprisingly I know something :shock:
You need to use the formula y=m * x^3 + c  => m= rise/run= 1/3
Therefore you get y= (1/3)x^3, making C the correct answer


Correct and then you test the points from the answers, making (1, (1/3)) correct which is C.

So the correct answers are:

Graphs and Relations

   1. D
   2. C
   3. E
   4. B
   5. D
   6. E
   7. C
   8. B
   9. A
Title: Exam 1 Graphs & Relations Answers
Post by: kjg on November 05, 2007, 03:43:55 pm
Quote from: "Mystery"
Quote from: "Odette"
Quote from: "Nick"
Can someone explain to me how it can't be E?


Oh i know... :shock:...surprisingly I know something :shock:
You need to use the formula y=m * x^3 + c  => m= rise/run= 1/3
Therefore you get y= (1/3)x^3, making C the correct answer


Correct and then you test the points from the answers, making (1, (1/3)) correct which is C.

So the correct answers are:

Graphs and Relations

   1. D
   2. C
   3. E
   4. B
   5. D
   6. E
   7. C
   8. B
   9. A


ohhh, i hope i quoted this thingy right haha

ok, graphs and realtions, q6) E?
why E? wouldn't it be B?
I stuffed up question 7 haha, woopsie, i didn't see that the x axis had already been transformed

did anyone find this years exams so much harder than expected
i cried afterwards
Title: Exam 1 Graphs & Relations Answers
Post by: Odette on November 05, 2007, 03:50:25 pm
It's E because he needs to make AT LEAST twice as many bottles of RED wine (x) as white wine (y)
Therefore its x>/= 2y

Ok ok im going now people, adios =]
Title: Exam 1 Graphs & Relations Answers
Post by: Lyonzy on November 05, 2007, 07:41:47 pm
I find its sometimes easier to consider them equal before thinking about the inequality, for example:
"This year he plans to make twice as many bottles of red as white"
and then its easier to see that r=2w (or x=2y)
...or you could also do a diagram, and check you've got twice as much red as white.
Title: Exam 1 Graphs & Relations Answers
Post by: gangreen on November 05, 2007, 08:52:22 pm
Quote from: "Odette"
Oh i know... :shock:...surprisingly I know something :shock:
You need to use the formula y=m * x^3 + c  => m= rise/run= 1/3
Therefore you get y= (1/3)x^3, making C the correct answer
Using the points in Option C (1, 1/3), you get the right answer ...
If you want me to explain it further just let me know


it took me a bit but i get it now. i had the gradient but i sort of lost the plot after that (plot hah - feel free to use that one lads)