2010 MM Exam 2 suggested solutions

[lisafaustina]

ARGHHHHHHH I FOUND x FOR THE VOLUME QUESTION BUT I ASSUMED IT MUST BE WRONG AND WROTE PI........WHAT A FKN IDIOT I AM.

[Whatlol]

Good job Mao +karma

[Mao]

hey with question 2.3e with dT/dx shouldnt it be a negative sign before 12cos(x)^5sin(x) blabla

Nope, that's a positive.

[becca92]

in 2.4.b did we have to find the coordinates or was x =1/a and x =(1+ab)/4a an adequate answer?

[jane1234]

in 2.4.b did we have to find the coordinates or was x =1/a and x =(1+ab)/4a an adequate answer?

The question just asked for what x-values are there a stationary point, so i dont think co-ordinates were needed ...

[lisafaustina]

hey mao, what do you reckon the A+ cut off will be?

[luffy]

wow - nice solutions.

When I entered that dT/dx question into my CAS. I got 2tan^-1 ((root6 - root 2)/root3). Turns out that is the same as cos^-1(1/root3). Will I lose marks? However, when I found the volume, I got a really long answer haha.

Could you guys please tell me how you got the cos^-1 answer. Even when I try it now, I get the same answer. How did you guys do it?

[Mao]

in 2.4.b did we have to find the coordinates or was x =1/a and x =(1+ab)/4a an adequate answer?

The question just asked for what x-values are there a stationary point, so i dont think co-ordinates were needed ...

^^this. I stated the coordinates for completeness, and also that later parts required the coordinates.

hey mao, what do you reckon the A+ cut off will be?

I did say I won't be making a prediction.

[jimmy999]

wow - nice solutions.

When I entered that dT/dx question into my CAS. I got 2tan^-1 ((root6 - root 2)/root3). Turns out that is the same as cos^-1(1/root3). Will I lose marks? However, when I found the volume, I got a really long answer haha.

Could you guys please tell me how you got the cos^-1 answer. Even when I try it now, I get the same answer. How did you guys do it?

If the question just asked for an exact answer, then that should be okay. However if it specified what form it needs to be in, then marks can be taken off

[Mao]

wow - nice solutions.

When I entered that dT/dx question into my CAS. I got 2tan^-1 ((root6 - root 2)/root3). Turns out that is the same as cos^-1(1/root3). Will I lose marks? However, when I found the volume, I got a really long answer haha.

Could you guys please tell me how you got the cos^-1 answer. Even when I try it now, I get the same answer. How did you guys do it?

It will be accepted. An examiner who runs across this will double check when he/she sees it (if he/she is not an idiot, and they generally tend to be fairly good).

Following the steps of my workings in the solutions, it was just an application of the null factor theorem.

[jayna]

in 2.4.b did we have to find the coordinates or was x =1/a and x =(1+ab)/4a an adequate answer?

The question just asked for what x-values are there a stationary point, so i dont think co-ordinates were needed ...

^^this. I stated the coordinates for completeness, and also that later parts required the coordinates.

hey mao, what do you reckon the A+ cut off will be?

I did say I won't be making a prediction.

Did you find it harder than 07?

*PRAYS* please say yes. By a long shot. *Ends Prayer*

[axilon]

wow - nice solutions.

When I entered that dT/dx question into my CAS. I got 2tan^-1 ((root6 - root 2)/root3). Turns out that is the same as cos^-1(1/root3). Will I lose marks? However, when I found the volume, I got a really long answer haha.

Could you guys please tell me how you got the cos^-1 answer. Even when I try it now, I get the same answer. How did you guys do it?

It will be accepted. An examiner who runs across this will double check when he/she sees it (if he/she is not an idiot, and they generally tend to be fairly good).

Following the steps of my workings in the solutions, it was just an application of the null factor theorem.

so if you did use inverse tan etc and u got an extremely large expression for the volume will you still get the marks if its unsimpliflied?
the answer took up a whole line lol.
or are we looking at max 3/4??

[Whatlol]

wow - nice solutions.

When I entered that dT/dx question into my CAS. I got 2tan^-1 ((root6 - root 2)/root3). Turns out that is the same as cos^-1(1/root3). Will I lose marks? However, when I found the volume, I got a really long answer haha.

Could you guys please tell me how you got the cos^-1 answer. Even when I try it now, I get the same answer. How did you guys do it?

It will be accepted. An examiner who runs across this will double check when he/she sees it (if he/she is not an idiot, and they generally tend to be fairly good).

Following the steps of my workings in the solutions, it was just an application of the null factor theorem.

so if you did use inverse tan etc and u got an extremely large expression for the volume will you still get the marks if its unsimpliflied?
the answer took up a whole line lol.
or are we looking at max 3/4??

same thing happened to me

[98.40_for_sure]

^ yep. this. the answer was right, however a moronic examiner might be like mm nope this isnt what i have on my answer sheet! -1 -1 -1 -1 until all your marks are gone

[TrueTears]

Good man Mao, I was gonna do it right now coz I finished my exams but yours look great, champ!