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# AQA Core 3 - Thursday 6th June 2013 (AM) - Official Thread watch

1. (Original post by edina101morris)
urmm there was a ln one as well i think it was y= ln(3x+2) and then you had to do the inverse of it?
y=(e^3x)/2 for f^-1(x) then you do a graph for that? Is the inverse of f(x) right?
2. why are such few people posting on here? for chem and bio there are so many normally
3. (Original post by ryanc_95)
for the last one i got 2ln2+2. A few people have also said they got this, is this correct or is it 2ln(3/2)?

I checked on my graphical calculator, it said 0.801 something. And 2ln(3/2) is around about that. So i stuck with 2ln(3/2)
4. (Original post by AunShah)
For the transformation question f=(x) to f=(-2x) did it matter, which order you did the transformation in??
I put (reflection in the y axis) and then (stretch scale factor 0.5 in x axis), I think. Would that be right?
i also want to know this! i put stretch first and then reflection and then kept doubting myself whether the order mattered!?
5. i reckon it will be similar to jan 13 grade boundary wise as the A* mark has never been higher than 69 for C3, and i thought 69 for an A* was high for january considering the last part of the paper was fairly challenging? I'm predicting around 67-69 for an A*, hoping its towards the lower end as i made some really basic errors
6. (Original post by edina101morris)

edit: ignore just seen you're other post

do you know which order we had to write the transformations in? was it reflect first the stretch or does it not matter?
I put the stretch then the reflection if I remember correctly and I think it does matter which way it goes...thats what weve always been told anyway. We got told this little order in which we had to do things put X Translation first then Xstretch then X reflection then Y Reflection then Y stretch then Y Translation but I think all teachers and stuff do it differently
7. (Original post by AunShah)
Very last question, bummed me over because I was being stupid. I know I've lost a few here and there, but hopefully I've done enough to get close to an A which would help. Do you think grade boundaries will be similar to Jan 13 core 3, higher or maybe ever lower?
Oioi WAAAASSTTEEEMAANNN

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8. (Original post by AunShah)
For the transformation question f=(x) to f=(-2x) did it matter, which order you did the transformation in??
I put (reflection in the y axis) and then (stretch scale factor 0.5 in x axis), I think. Would that be right?
Pretty sure that's what I got. I wrote it out the other way round, but I don't think the order mattered
9. (Original post by AunShah)
Very last question, bummed me over because I was being stupid. I know I've lost a few here and there, but hopefully I've done enough to get close to an A which would help. Do you think grade boundaries will be similar to Jan 13 core 3, higher or maybe ever lower?
Felt like crying bro. So frustrating. Gonna have to get me a good A on monday!

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10. I got 160pi/3 for the vase question and 5.05 and 1.23 for the 7 mark question with sec squared in.

I think for the f(|x|) graph you had to reflect the right hand side of the graph in the y axis from what i've seen in a past paper, not sure if it was right in this situation though.

I think it was a stretch in the x direction of scale factor 2 followed by a reflection in the y axis, but doesn't matter which way round it was.

I got like 1/2ln(2/3) for a question as well.. most of it you could check on the calculator which was nice!

Does anyone remember the other questions?
11. (Original post by Relf)
y=(e^3x)/2 for f^-1(x) then you do a graph for that? Is the inverse of f(x) right?
hang on, i think y=(2x-3)

then think f-1(x) was (e^x+3)/2

not sure cant quite remeber
12. (Original post by stuart_aitken)
For the -f(3x) graph, I reflected it in the x-axis, with the x-intercept at (2,0) because of the 1/3 stretch (original x-intercept was (6,0), and the y-intercept remained at (0,4)

For f|x| I just drew the original graph but bounced it off the x-axis when it hit, so everything stayed in the upper two quadrant. Opinion on this below..

And opinions on that?
I thought you had to give a reflection of the top right hand quadrant in the y axis for f|x|, the one where you bounce everything off the x - axis is |fx|
13. (Original post by Anon217)
Pretty sure that's what I got. I wrote it out the other way round, but I don't think the order mattered
same i hope order doesnt matter
14. (Original post by edina101morris)
i also want to know this! i put stretch first and then reflection and then kept doubting myself whether the order mattered!?
I can't remember in all honesty which way I did it too :s !
15. (Original post by beccac94)
I put the stretch then the reflection if I remember correctly and I think it does matter which way it goes...thats what weve always been told anyway. We got told this little order in which we had to do things put X Translation first then Xstretch then X reflection then Y Reflection then Y stretch then Y Translation but I think all teachers and stuff do it differently
oh okay i did put stretch first so hopefully i got lucky there
16. (Original post by nothepreacher)
the graph you have drawn is wrong. It is supposed to be reflected in x axis and not y
Ummmmm. I didn't draw it. My graph software did!

There's the logic/

y = pi - cos^-1(x)
It's define for -1<x<1, because cos# cannot be outside this range. Therefore the limits for x are -1 to +1. So for the important values:

x= -1
y = pi - cos^-1(-1) = pi - pi = 0
(-1,0)>>>end point

x = 0
y = pi - cos^-1(0) = pi - pi/2) = pi/2
(0,pi/2)>>>y-intercept

x = 1,
y = pi-cos^1(1) = pi - 0 = pi
(1,pi)>>>end point

As can be seen from these results, the graph I drew is surely correct
17. (Original post by edina101morris)
same i hope order doesnt matter
Yeah I think for certain questions the order can matter, but not for this one
18. (Original post by Icycandle)
I thought you had to give a reflection of the top right hand quadrant in the y axis for f|x|, the one where you bounce everything off the x - axis is |fx|
You're probably right. Not gonna lie.... I did one practice paper in the last 6 months since I originally sat the exam... I completely forgot about these kinds of questions
19. (Original post by Anon217)
Yeah I think for certain questions the order can matter, but not for this one
yeah i hate those questions i always screw them up!
20. [QUOTE=Dinomouse;43004567]I got 160pi/3 for the vase question and 5.05 and 1.23 for the 7 mark question with sec squared in.

For the volume question, I got the answer as 73/3 pi and checked in my calculator and it was the same?

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