Carrotsticks' Solutions 2015 Extension 1 HSC (3 Viewers)

[eccentricity]

If it asks us to find the angle that the projectile makes with the horizontal are we supposed to put pi/6 or pi-pi/6=5pi/6?

 

[Carrotsticks]

for 14ci, im not sure how but I ended up proving what they wanted via 7c5-6c5=6c4... will i get the mark with that?

Of course! That is most certainly valid.

 

[Carrotsticks]

If it asks us to find the angle that the projectile makes with the horizontal are we supposed to put pi/6 or pi-pi/6=5pi/6?

Either pi/6 or -pi/6 would have been accepted. 5pi/6 is just incorrect, as it implies that the particle is moving backwards.

 

[rahulnimmagadda]

Isn't the 3D trig 62m?

 

[rahulnimmagadda]

WOOOOOOOOOOOOOOOOOOW RIP RIP RIP RIP, my calculators in Rad mode.

 

[Carrotsticks]

Isn't the 3D trig 62m?

That's a very short mountain then.

It's too late now for you, but for this reason I always tell my students to verify their answer with what makes sense in real life. Is your answer reasonable? If not, double check it.

So if I got a 62m high mountain, I'd immediately be suspicious.

 

[Zlatman]

I did both of these (y/x and ydot/xdot), but crossed out the ydot/xdot answer (which was correct), can I still get both marks or would I lose one because my non-crossed-out answer was incorrect?

 

[Carrotsticks]

I did both of these (y/x and ydot/xdot), but crossed out the ydot/xdot answer (which was correct), can I still get both marks or would I lose one because my non-crossed-out answer was incorrect?

Hard to say for this one. I am leaning more towards you losing the mark here.

 

[Zlatman]

Hard to say for this one. I am leaning more towards you losing the mark here.

Ahh well, I guess it makes sense, wasn't really hopeful anyway (fingers crossed though).

Thanks for the quick response!

 

[ENFP]

4 other things:
1. I'm not sure, but i might have done 11m/s instead of root(11)m/s for 13aii, will they dock for that if i didnt put root?
2. in 14bi, I went with the -(x-1) and crossed out the (x-1) for +-(x-1) without actually specifying why the (x-1) was cancelled out, so they'll dock for that, won't they? Unless they're nice.
3. In 14bii, i think I wrote e^t rather than e^-t, is that significant enough to lose a mark?
4. In 11c, how many marks would be lost for writing -3<=x<=1 instead of -3<x<=1?

 

[QuantumRoulette]

If, for question 14 b ii I wrote t as a function of x, but in b iii I made x the subject, and the proceeded to get the correct answer would I get full marks for both parts? Also in q14 a ii if I forgot to cancel the g's in ydot expression and didn't get the proper answer of pi/6 would I lose a mark? And in the next part of that q would I lose a mark for saying it was up when my previous answer dictated it should be? Or would I get CFPA? ALSO in q13 a iii if I said a=4 mistakenly, and because of this I found n to be sqrt(11)/4, would I get 2/3?

 

[Carrotsticks]

4 other things:
1. I'm not sure, but i might have done 11m/s instead of root(11)m/s for 13aii, will they dock for that if i didnt put root?
2. in 14bi, I went with the -(x-1) and crossed out the (x-1) for +-(x-1) without actually specifying why the (x-1) was cancelled out, so they'll dock for that, won't they? Unless they're nice.
3. In 14bii, i think I wrote e^t rather than e^-t, is that significant enough to lose a mark?
4. In 11c, how many marks would be lost for writing -3<=x<=1 instead of -3<x<=1?

1. Yes, you would've lost a mark for it. I can imagine that was the specific trap set in mind for this question actually.

2. Yes, they'll dock you a mark for not justifying your choice. It is a 3 mark question after all.

3. If everything else was e^(-t) and you just wrote e^t in your last line, that's a transcription error and you would've received full marks still. However, if everything was in terms of e^t, you would've lost a mark definitely.

4. 1 mark only.

 

[ENFP]

1. Yes, you would've lost a mark for it. I can imagine that was the specific trap set in mind for this question actually.

2. Yes, they'll dock you a mark for not justifying your choice. It is a 3 mark question after all.

3. If everything else was e^(-t) and you just wrote e^t in your last line, that's a transcription error and you would've received full marks still. However, if everything was in terms of e^t, you would've lost a mark definitely.

4. 1 mark only.

3. I would have had a -t there until i put it all to the power of e, so it was lost in my last or 2nd last line of working.

 

[invisible036]

What would 58/60/61 aligned to guys? Thanks !

 

[Carrotsticks]

3. I would have had a -t there until i put it all to the power of e, so it was lost in my last or 2nd last line of working.

Most likely a transcription error then, but this one I cannot say for certain.

If, for question 14 b ii I wrote t as a function of x, but in b iii I made x the subject, and the proceeded to get the correct answer would I get full marks for both parts? Also in q14 a ii if I forgot to cancel the g's in ydot expression and didn't get the proper answer of pi/6 would I lose a mark? And in the next part of that q would I lose a mark for saying it was up when my previous answer dictated it should be? Or would I get CFPA? ALSO in q13 a iii if I said a=4 mistakenly, and because of this I found n to be sqrt(11)/4, would I get 2/3?

Most likely you would've been awarded full marks for both parts still. HSC markers are very reasonable.

What answer did you acquire for Q14 (a) (ii) then?

Most likely CFPA for that one.

You would get 2/3 definitely.

What would 58/60/61 aligned to guys? Thanks !

90-91 roughly perhaps, or a 45/50. Possibly 46/50.

 

[Pab]

In Q13 B i) and ii), if I left it in the form with the x's still in there would I lose 2 marks?

 

[Carrotsticks]

In Q13 B i) and ii), if I left it in the form with the x's still in there would I lose 2 marks?

For part (i) you probably would've lost a mark for leaving the x there, as a_2 is unambiguously the coefficient, not the term.

For part (ii), I'm not sure how you would've still had x's in there unless you had something like x^0, in which case that is still okay.

 

[ENFP]

How many units in terms of the ATAR does 3U Maths count for? I've been told 3 by some and 2 by others (given that I'm doing Extension 2 Maths as well)

 

[Pab]

For part (i) you probably would've lost a mark for leaving the x there, as a_2 is unambiguously the coefficient, not the term.

For part (ii), I'm not sure how you would've still had x's in there unless you had something like x^0, in which case that is still okay.

I left it like this and this

 

[Carrotsticks]

How many units in terms of the ATAR does 3U Maths count for? I've been told 3 by some and 2 by others (given that I'm doing Extension 2 Maths as well)

If you are doing Extension 2 Maths, it counts as 2 units.

If you are doing Extension 1 as well as Advanced, it counts as 1 unit.