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March 29, 2024, 01:47:08 am

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RuiAce

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Mathematics Question Thread
« Reply #495 on: October 15, 2016, 11:06:53 am »
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asd987

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Re: Mathematics Question Thread
« Reply #496 on: October 15, 2016, 11:14:10 am »
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I'm stuck on part b) of the question, but this includes the whole thing: A farmer wants to make a rectangular paddock with an area of 4000m^2. However, fencing costs are high and she wants the paddock to have a minimum perimeter. a) Show that the perimeter is given by the equation P = 2x + 8000/x b) Find the dimensions of the rectangle that will give the minimum perimeter, correct to 1 decimal place.



RuiAce

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Mathematics Question Thread
« Reply #497 on: October 15, 2016, 11:18:04 am »
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I'm stuck on part b) of the question, but this includes the whole thing: A farmer wants to make a rectangular paddock with an area of 4000m^2. However, fencing costs are high and she wants the paddock to have a minimum perimeter. a) Show that the perimeter is given by the equation P = 2x + 8000/x b) Find the dimensions of the rectangle that will give the minimum perimeter, correct to 1 decimal place.




julzzz

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Re: Mathematics Question Thread
« Reply #498 on: October 15, 2016, 11:29:42 am »
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(Sorry new to this - don't know how to reply to one comment on its own...)

In reference to my differentiation and nation of SP question, I tried testing points on either side but it doesn't match up to the answers or what the actual graph looks like.
Could you solve it and let me see if my answers match. The 2 SP I got were (5, 20) and (-5,-20). I thought the first was the minimum and the second a maximum.

Thanks in advance.

RuiAce

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Re: Mathematics Question Thread
« Reply #499 on: October 15, 2016, 11:34:32 am »
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(Sorry new to this - don't know how to reply to one comment on its own...)

In reference to my differentiation and nation of SP question, I tried testing points on either side but it doesn't match up to the answers or what the actual graph looks like.
Could you solve it and let me see if my answers match. The 2 SP I got were (5, 20) and (-5,-20). I thought the first was the minimum and the second a maximum.

Thanks in advance.
Can you please show me your working out? There's guides to how you can upload images onto this forum if you don't want to type it.

Or you can upload through the ATARnotes app.

julzzz

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Re: Mathematics Question Thread
« Reply #500 on: October 15, 2016, 11:59:01 am »
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Can you please show me your working out? There's guides to how you can upload images onto this forum if you don't want to type it.

Or you can upload through the ATARnotes app.

Ok, so my differentiation is in my working.

I used the table in the picture to figure out if it was the maximum or minimum. For (5,20), because it is negative before and positive after, I thought that would make it a minimum but the answers have maximum. Turns out my diagram isn't right according to geogebra so ignore that btw.
I haven't learnt using second derivatives, but am keen to learn it if helps me understand the question.

Thanks again

RuiAce

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Re: Mathematics Question Thread
« Reply #501 on: October 15, 2016, 12:04:41 pm »
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Ok, so my differentiation is in my working.

I used the table in the picture to figure out if it was the maximum or minimum. For (5,20), because it is negative before and positive after, I thought that would make it a minimum but the answers have maximum. Turns out my diagram isn't right according to geogebra so ignore that btw.
I haven't learnt using second derivatives, but am keen to learn it if helps me understand the question.

Thanks again
Its 2x+50/x right?

I'm pretty sure that (5,20) is a minimum and (-5,-20) is a maximum. GeoGebra should confirm that.

One thing to note: the graph has an asymptote at x=0. You have to analyse this separately.

BPunjabi

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Re: Mathematics Question Thread
« Reply #502 on: October 15, 2016, 01:17:42 pm »
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Hey Rui!

Need help for the whole question please!

Did HSC in 2016 and was first person to get 100. Aeronautical engineering for me now :P
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RuiAce

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Re: Mathematics Question Thread
« Reply #503 on: October 15, 2016, 01:32:37 pm »
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Hey Rui!

Need help for the whole question please!

(Image removed from quote.)


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justdoit

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Re: Mathematics Question Thread
« Reply #504 on: October 15, 2016, 01:39:40 pm »
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Hi, can someone please help me with the 2015 q.16 c. Looked at the working out and cant understand it :/

Thank youuu :)

RuiAce

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Re: Mathematics Question Thread
« Reply #505 on: October 15, 2016, 01:47:43 pm »
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Hi, can someone please help me with the 2015 q.16 c. Looked at the working out and cant understand it :/

Thank youuu :)

In the future please provide a link to the paper or the question





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« Last Edit: October 15, 2016, 01:57:19 pm by RuiAce »

kevin217

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Re: Mathematics Question Thread
« Reply #506 on: October 15, 2016, 02:28:02 pm »
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What are the steps to graphing this sine curve?

RuiAce

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justdoit

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Re: Mathematics Question Thread
« Reply #508 on: October 15, 2016, 02:42:04 pm »
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 Hi, thanks for the help but how did u get 2R/3

RuiAce

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Re: Mathematics Question Thread
« Reply #509 on: October 15, 2016, 02:50:25 pm »
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Hi, thanks for the help but how did u get 2R/3