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March 29, 2024, 12:54:22 am

Author Topic: Mathematics Question Thread  (Read 1296734 times)  Share 

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nimasha.w

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Re: Mathematics Question Thread
« Reply #540 on: October 15, 2016, 11:23:36 pm »
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Be more specific please? If you're given the function, say, f(x)=x3+3x2 then all you have to do is differentiate it and then continue.

Do you mean drawing the graph of the derivative, given the graph of the original thing?

sorry for the confusion!
like with (iii) i could get it all except from t1 to t3

asd987

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Re: Mathematics Question Thread
« Reply #541 on: October 15, 2016, 11:29:43 pm »
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I need help with this question please

A surfboard is in the shape of a rectangle and semicircle. The perimeter is to be 4m. Find the maximum area of the surfboard, correct to 2 decimal places.

RuiAce

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Re: Mathematics Question Thread
« Reply #542 on: October 15, 2016, 11:43:34 pm »
+1
I need help with this question please

A surfboard is in the shape of a rectangle and semicircle. The perimeter is to be 4m. Find the maximum area of the surfboard, correct to 2 decimal places.
Draw a diagram and show us your working out thus far, like how I used a diagram for your earlier question. You cannot simply do those questions without a diagram.
sorry for the confusion!
like with (iii) i could get it all except from t1 to t3



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kevin217

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Re: Mathematics Question Thread
« Reply #543 on: October 16, 2016, 10:36:28 am »
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Depending on whether a function is concave up or down, how does Simpsons rule over/underestimate the exact area?

RuiAce

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Re: Mathematics Question Thread
« Reply #544 on: October 16, 2016, 10:43:03 am »
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Depending on whether a function is concave up or down, how does Simpsons rule over/underestimate the exact area?
Recall that Simpson's rule uses a parabolic arc to estimate the area.

Given any three points, sketch a parabola through them. Look at whether the area under the parabola is greater than, or less than the original area.

Note that the concavity of the function itself isn't enough for Simpson's rule. For the trapezoidal rule it is all that's needed because you're estimating with just trapeziums (and hence you draw straight lines). For Simpson's rule, you need to physically consider what the parabola through the three points looks like to make a conclusion. An example of where this was needed was in the 2013 HSC.

kevin217

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Re: Mathematics Question Thread
« Reply #545 on: October 16, 2016, 11:13:16 am »
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Recall that Simpson's rule uses a parabolic arc to estimate the area.

Given any three points, sketch a parabola through them. Look at whether the area under the parabola is greater than, or less than the original area.

Note that the concavity of the function itself isn't enough for Simpson's rule. For the trapezoidal rule it is all that's needed because you're estimating with just trapeziums (and hence you draw straight lines). For Simpson's rule, you need to physically consider what the parabola through the three points looks like to make a conclusion. An example of where this was needed was in the 2013 HSC.
I see, thanks

MysteryMarker

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Re: Mathematics Question Thread
« Reply #546 on: October 16, 2016, 06:55:22 pm »
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For question 15c, could someone explain to me how to do it both graphically and algebraically. Isn't that if I equate the two expressions, square them and solve for their discriminant to = 0, i should get a value for m? (I tried and its not working, just curious as to why).

Thanks.

RuiAce

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Re: Mathematics Question Thread
« Reply #547 on: October 16, 2016, 07:39:50 pm »
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For question 15c, could someone explain to me how to do it both graphically and algebraically. Isn't that if I equate the two expressions, square them and solve for their discriminant to = 0, i should get a value for m? (I tried and its not working, just curious as to why).

Thanks.
The graphical method was done in post #454
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epherbertson

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Re: Mathematics Question Thread
« Reply #548 on: October 16, 2016, 07:56:53 pm »
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Help
This is from question 10 of the 1995 paper and am having trouble with the working of the question. I got part I out but i am lost from there. any help would be largely appreciated...
Thanks
Emily :-\

imtrying

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Re: Mathematics Question Thread
« Reply #549 on: October 16, 2016, 08:13:59 pm »
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Hey:) Just need a hand with this question from the 2012 paper. I've tried looking at the solutions but they just arent making sense to me. Thanks!
Year 12 2016 (94.20)
English (Adv), Maths Ext.1, Modern History, Biology and Physics

RuiAce

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Re: Mathematics Question Thread
« Reply #550 on: October 16, 2016, 08:23:40 pm »
+1
Hey:) Just need a hand with this question from the 2012 paper. I've tried looking at the solutions but they just arent making sense to me. Thanks!







imtrying

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Re: Mathematics Question Thread
« Reply #551 on: October 16, 2016, 08:28:38 pm »
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Thanks so much, your explanation really helped:)
Year 12 2016 (94.20)
English (Adv), Maths Ext.1, Modern History, Biology and Physics

RuiAce

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Re: Mathematics Question Thread
« Reply #552 on: October 16, 2016, 08:41:43 pm »
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Help
This is from question 10 of the 1995 paper and am having trouble with the working of the question. I got part I out but i am lost from there. any help would be largely appreciated...
Thanks
Emily :-\
The question says to show us part a) so please link part a) next time.


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Part (iv) cannot be done because you don't know how to solve -6+2t-t2/2 = 4sin(t)

Hence, try a graphical approach.

You may find the solutions here

cajama

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Re: Mathematics Question Thread
« Reply #553 on: October 17, 2016, 09:24:10 am »
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Hello, I'm not sure if this question has been answered before and I know it's been talked about in one of the ATARNotes Maths lectures but are we still allowed to use abbreviations in the reasonings (e.g. isosceles Δ abbreviated to isos.Δ / supplementary to supp.)? A friend of mine said that this year, we wouldn't be allowed to use them and I'm just a little confused.

RuiAce

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Re: Mathematics Question Thread
« Reply #554 on: October 17, 2016, 09:37:13 am »
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Hello, I'm not sure if this question has been answered before and I know it's been talked about in one of the ATARNotes Maths lectures but are we still allowed to use abbreviations in the reasonings (e.g. isosceles Δ abbreviated to isos.Δ / supplementary to supp.)? A friend of mine said that this year, we wouldn't be allowed to use them and I'm just a little confused.
I haven't heard anything about this (maybe the two other mods will input further).

Personally I always chose when to abbreviate. At times, abbreviating is a convenient shorthand, but at other times it reduces the formality of your work and begins to read like laziness.