2014 HSC Mathematics Solutions (1 Viewer)

[Nukeboy]

It's 3 solutions for the MC question :/
Inversetan(-2) has two in the domain and sinx had one

Damn, but x can't equal to pi/2

 

[bongoli]

b5 cutoff boys??? i got 70/100 pls say i can b5 tyy

b5 is 64-66 probs
i'd say b6 is anywhere between a 79-85

 

[Nukeboy]

Just draw (sinx-1)(tanx+2) between 0 and 2pie. There are 3 roots, hence 3 solutions.

Just because your calculator says math error doesn't necessarily mean it doesn't count. There are times where algebra is incorrect.

Really? Wouldn't it be undefined at that point?

 

[Nukeboy]

Really? Wouldn't it be undefined at that point?

Maybe OP can clarify?

 

[photastic]

Really? Wouldn't it be undefined at that point?

No, the two functions are multiplied, hence the asymptotes of the standard tanx is no longer at pie/2. I've been using different graphical applications and they are showing 3 roots, same with wolfram alpha.

 

[Nukeboy]

No, the two functions are multiplied, hence the asymptotes of the standard tanx is no longer at pie/2. I've been using different graphical applications and they are showing 3 roots, same with wolfram alpha.

Oh wow I hope you are right. But would they expect you to consider all that in 2u?
Change in asymptotes etc

 

[ymcaec]

Really? Wouldn't it be undefined at that point?

Just draw (sinx-1)(tanx+2) between 0 and 2pie. There are 3 roots, hence 3 solutions.

Just because your calculator says math error doesn't necessarily mean it doesn't count. There are times where algebra is incorrect.

Hmm I see your point. Didn't pick it up while I was rushing through it.
It could be an open circle on the graph (i.e. approaching 0) so there might only be two solutions.

 

[ymcaec]

Oh wow I hope you are right. But would they expect you to consider all that in 2u?
Change in asymptotes etc

Don't know if it's a trick question or not haha. (doesn't look like it though)

 

[Nukeboy]

Hmm I see your point. Didn't pick it up while I was rushing through it.
It could be an open circle on the graph (i.e. approaching 0) so there might only be two solutions.

So how would you determine the answer? Like Aaron said, wolfram alpha does show a root at pi/2. But my calc and a graphing calc says otherwise.
Would they end up putting 2 correct answers? That would be great

 

[photastic]

Hmm I see your point. Didn't pick it up while I was rushing through it.
It could be an open circle on the graph (i.e. approaching 0) so there might only be two solutions.

Confirming that these graphs can't pick up open circles, therefore I think the answer is B algebraically but hoping C cos I spent so much time graphing it lol

 

[Chocolatebubble]

Confirming that these graphs can't pick up open circles, therefore I think the answer is B algebraically but hoping C cos I spent so much time graphing it lol

Don't some papers have answers like "B OR C"?

 

[photastic]

Don't some papers have answers like "B OR C"?

I've seen many science papers have 2 or even 0 answers but this is something the mathemagicians will decide.

 

[chrisdelinet]

I've seen many science papers have 2 or even 0 answers but this is something the mathemagicians will decide.

agreed, i hope there will be a huge debate going over a bostes atm. it'll be war with protractors flying, calculators smashing, circles destroyed, etc.

 

[chrisdelinet]

Nek minute, its not B or C

wow, now that will be something ...

 

[Carrotsticks]

The answer for question 7 is (B) without a doubt.

I'm not too sure why there is so much debate going on here over that, as x clearly cannot be pi/2. I addressed this silly error in the multiple choice of my BOS Trials for 2U as well, this very same trap.

 

[bongoli]

The answer for question 7 is (B) without a doubt.

I'm not too sure why there is so much debate going on here over that, as x clearly cannot be pi/2. I addressed this silly error in the multiple choice of my BOS Trials for 2U as well, this very same trap.

Why can't x= pi/2 ?

 

[photastic]

Why can't x= pi/2 ?

Cos tan(pi/2) is undefined. Well there goes my atar.

 

[enigma_1]

Cos tan(pi/2) is undefined. Well there goes my atar.

what a retarded question

I just realised what you guys are on about with the tan pi/2 thing (((
#typicalbostes

 

[photastic]

what a retarded question

I just realised what you guys are on about with the tan pi/2 thing (((
#typicalbostes

Already lost 10 marks, without sillies, fml

 

[enigma_1]

Already lost 10 marks, without sillies, fml

Same ((((