Math Ext 1 Predictions/Thoughts (1 Viewer)

notme123

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that sucks why are they so pedantic with this? i really cant remember if i labelled or not but i dont think i did

i dont think its fair to lose a whole mark if my sketch is entirely correct with the default axes
 

one eight seven

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Okay this is ridiculous if the students had the old version then something seriously wrong is going on.
The slope field during the exam was not wrong. The slope field with the swapped x and y axis was a recreation that I had requested someone on ConquerHSC to make for me so that I could write up a set of solutions, since I only had a poor quality photo version of it. They recreated each dash on the slope field by hand and simply made an error, mislabelling the axis.

tywebb had incorrectly credited the source of the slope field diagram when he took it off ConquerHSC and thought it was the official HSC version. I guess the recreation was so good, everyone thought it was the real deal!

A lot of items here such as the scanned copy of HSC paper posted on Friday night, my set of solutions, Nash's set of solutions, the slope field diagram, andy!'s solution to the slope field diagram were all taken off ConquerHSC and reposted here.
 
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uart

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The slope field during the exam was not wrong. The slope field with the swapped x and y axis was a recreation that I had requested someone on ConquerHSC to make for me so that I could write up a set of solutions
Ok thanks, I wondered how that happened.

Okay this is ridiculous if the students had the old version then something seriously wrong is going on.
It's a complete a non-issue. You had to draw your solution on the graph provided, so irrespective of how x and y were labelled your solution just had to match the graph as given.

It was pretty much just "joining the dots" anyway, and as with all graphical solution an approx result is good enough. You did have to be a bit careful to get at least moderate accuracy though (such as interpolating the gradient between marked points), as "P" was kind of close to a bifurcation point.
 

tywebb

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Terry Lee's solutions: http://advancedmathematics.com.au/Resources/2021 Ext1.pdf

He (like matrix) also has said that both solutions are OK for 12a. It will be interesting what will be said at the HSC feedback day next year. At this event the senior markers report on each question that was marked in the previous year's HSC exams. It is usually held on the last Saturday in February at Macquarie University. This year it was on youtube due to covid at https://www.youtube.com/channel/UCYWgSDiUVcDEorLosTqp8Bg/playlists . Not sure about next year though. If Omicron variant of covid comes to Australia we might all be in lockdown again and it might be on youtube again.
 
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jyu

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Terry Lee's solutions: http://advancedmathematics.com.au/Resources/2021 Ext1.pdf

He (like matrix) also has said that both solutions are OK for 12a. It will be interesting what will be said at the HSC feedback day next year. At this event the senior markers report on each question that was marked in the previous year's HSC exams. It is usually held on the last Saturday in February at Macquarie University. This year it was on youtube due to covid at https://www.youtube.com/channel/UCYWgSDiUVcDEorLosTqp8Bg/playlists . Not sure about next year though. If Omicron variant of covid comes to Australia we might all be in lockdown again and it might be on youtube again.
Not possible to draw another smooth curve going into the third quad because it does not follow the slopes in the last two fields in the second quad near the x-axis. Must look at it closely.
 

tywebb

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Not possible to draw another smooth curve going into the third quad because it does not follow the slopes in the last two fields in the second quad near the x-axis. Must look at it closely.
Yeah. I reckon most people agree it should be like the blue one. Nevetheless some had done it like the red one.

The question remains would the markers accept the red one? We won't know till HSC feedback day next year. (And as for markers comments posted on NESA's website - they usually wait till after the Feedback day before posting those up)
 
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uart

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Yeah. I reckon most people agree it should be like the blue one. Nevetheless some had done it like the red one. The question remains would the markers accept the red one?
Yeah, it definitely should be like the blue one, and it kind of needs some sloppy working to get that red soln. Look for example at the column of slope lines immediately to the right of P (at x about -0.8). There you can see that TL's red solution had to take a gradient that was significantly more negative than either the slope line directly above or the one directly below. It's literally like being asked to interpolate a number between 8 and 12, and coming up with 15.

Having said that, the fact that it's only worth one mark might prompt them to accept either solution. Like they might feel a bit mean giving zero marks for solutions that did have the correct basic idea, but just sloppy working.
 
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