Q14 (2 Viewers)

[theholy1]

aside from volumes, how did people do 14b ii)? partial fractions?

yes.. it tells u too

 

[Nws m8]

fahk I swear 90% of the state stuffed up volumes question -.-

 

[motaba]

Anyone use parabolas to work out the height? And a straight line to work out the width? (for the volumes question)

why would you use a parabola when it's a circle?
anyway, i used a circle to find height and triangles to work out width

 

[qrpw]

I'm looking back at 14c the volumes question- and is it actually a circle? DA is r, but AB isn't r so it would be a parabola. It'll be too hard if it was for a 4 marker, and obviously their intent was for a circle but it looks a bit weird to me.

 

[NickGero]

For the volumes question, I used similar triangles to find out the length of the side of the rectangle in the triangle, but that's it? 1 mark you think?

 

[d0nkeyk0ng]

for 14. b) ii, if you wrote x(2x-3)/(x-1) in the form mx + b + a/(x-1) but got the wrong equation for line L, would you still get 1 mark?

I forgot about using long division for that question =(
Instead, I split up x(2x-3)/(x-1) into 2x - x/(x-1) and got 2x for the equation of L

I didn't realised I made this mistake until last night.

 

[kingkong123]

I'm looking back at 14c the volumes question- and is it actually a circle? DA is r, but AB isn't r so it would be a parabola. It'll be too hard if it was for a 4 marker, and obviously their intent was for a circle but it looks a bit weird to me.

I also thought this in the exam, and I worked out the length of AB thinking that the angled cross section was a part of an ellipse. It turned out to be really messy so i then assumed that the angled cross section was an arc of the circle and I ended up getting a much neater answer (which was the correct answer)

 

[brianphamm]

why would you use a parabola when it's a circle?
anyway, i used a circle to find height and triangles to work out width

I only used parabolas because the 'radii' weren't the same. One was r and the other was something else. Since the height is bounded by that part of the 'curve', I believed it couldn't be a circle. I still think it's not a circle now.. How ridiculous

 

[braintic]

This is actually a VERY easy question. What made it hard for many people was:
1. The question wasn't scaffolded.
2. The variable for integrating wasn't introduced - you had to do that yourselves.

Perhaps in future years people should get practice at doing questions without them being set up for them. In other words, jump straight to the last part (of volume questions at least). After all, doing a scaffolded question is NOT what real maths is about.

 

[Carrotsticks]

This is actually a VERY easy question. What made it hard for many people was:
1. The question wasn't scaffolded.
2. The variable for integrating wasn't introduced - you had to do that yourselves.

Perhaps in future years people should get practice at doing questions without them being set up for them. In other words, jump straight to the last part (of volume questions at least). After all, doing a scaffolded question is NOT what real maths is about.

Agreed.

I'd like to see more "Build me a book case" as opposed to "Here are the tools and the instruction manual, build me a book case".