Mathematics Question Thread

[RuiAce]

Hey,

I know that the answer to studying for maths is practice, practice, practice!

It's just I've done about 3 hsc papers in the last week and I've gotten around 60% every time, and I don't know how to improve that?
Should i just keep going with hsc papers?

I guess I'm just a little bit upset because maths is the subject I put the most work into and it's my worst subject.

Thanks guys,

Mary

If you're only doing past papers in exam conditions, relax and do not be scared to do open-book papers and out of those exam conditions.

Consider where the marks are being lost. How is it occurring? Some starting points to consider:
1. Silly mistakes
2. Not understanding the question
3. Not using key bits of information
4. Approaching it from the wrong method
5. Calculator problems
6. Inability to deduce a method

and more.

Carefully consider where, why and how the marks were lost, and make a resolution from there. Of course, you may choose to point to us how the marks are getting lost if you want further insight on those specific areas of concern.

[Fahim486]

Hey could someone pls explain to me how x was made the subject. Thanks!

[justwannawish]

Hey guys,

Just a quick question on sig figs. Does 2800 count as 2 sf or 4? And is the HSC consistent with significant figures across science and maths, because my chemistry teacher seems to think that NESA is wrong about how they do it

[RuiAce]

Hey could someone pls explain to me how x was made the subject. Thanks!

Hey guys,

Just a quick question on sig figs. Does 2800 count as 2 sf or 4? And is the HSC consistent with significant figures across science and maths, because my chemistry teacher seems to think that NESA is wrong about how they do it

It counts as two, three or four, and without further information we are not really able to deduce this.

However, in mathematics, whilst you are expected to know what significant figures are, you will not be given the same types of question like in science. You should probably ask this question again in the physics thread for appropriate treatment in physics (or chemistry if applicable).

[sidzeman]

Hey for this, shouldn't the expansion be 4n + 2?

[RuiAce]

Hey for this, shouldn't the expansion be 4n + 2?

They miscounted the number of terms. There's only 1+n terms; not 1+2n, as a consequence of the common ratio being \(a^2\) and not \(a\).

[justwannawish]

It counts as two, three or four, and without further information we are not really able to deduce this.

However, in mathematics, whilst you are expected to know what significant figures are, you will not be given the same types of question like in science. You should probably ask this question again in the physics thread for appropriate treatment in physics (or chemistry if applicable).

Sorry about that! Will post in the correct forum now

[JuliaPascale123]

[sidzeman]

(Image removed from quote.)

Not 100% sure on this at all but I'll give it a shot
a. a/q is ordering while bq is storage. We know that its cheaper to place large orders - therefore as "q" (ordered amount) goes up, total price C must go down - which is given by a/q (inverse relationship)

b. I think is just simple differentiation. I'll upload a picture showing what I did - I don't think theres any other way of doing this question?

[Mary_a]

If you're only doing past papers in exam conditions, relax and do not be scared to do open-book papers and out of those exam conditions.

Consider where the marks are being lost. How is it occurring? Some starting points to consider:
1. Silly mistakes
2. Not understanding the question
3. Not using key bits of information
4. Approaching it from the wrong method
5. Calculator problems
6. Inability to deduce a method

and more.

Carefully consider where, why and how the marks were lost, and make a resolution from there. Of course, you may choose to point to us how the marks are getting lost if you want further insight on those specific areas of concern.

Okay, thanks so much, I'll definitely try to work out what's going wrong.

Cheers,

Mary

[_____]

2013 paper:



Answer is D. Is this because the positive speed means that the particle is moving towards a min TP/point of inflexion on the displacement graph (bottoming out)? If it were a negative speed, would the graph instead be dropping off like the example below? Haven't quite got the x v a relationship figured out yet.

[RuiAce]

2013 paper:

(Image removed from quote.)

Answer is D. Is this because the positive speed means that the particle is moving towards a min TP/point of inflexion on the displacement graph (bottoming out)? If it were a negative speed, would the graph instead be dropping off like the example below? Haven't quite got the x v a relationship figured out yet.

(Image removed from quote.)

__________________


So here, it slows down as it moves towards the left.

[arunasva]

Can I get some help with part b ? TY famz

[RuiAce]

Can I get some help with part b ? TY famz

And here's the part where math "clashes" with what really happens. Technically here, you could argue that after an infinite amount of time has passed, the solvent has fully evaporated. But infinity is not a number, so that never happens. So technically it never fully evaporates; it just gets asymptotically closer to 0 volume but never quite gets there.

When the questions are worded this way, it's quite poor. Usually, they would specifically ask for the "limiting behaviour", or in this case the "limiting volume of the solvent". Not bluntly whether or not it will evaporate.

[davidss]

hey can someone help with part iii please. thx