R u the new zacken btw. U seem to know everything bout maths(Original post by RDKGames)
If you can do it with numbers then im sure you can figure out the letters...
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Year 13 Maths Help Thread
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 12082016 09:52

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 12082016 09:59
(Original post by physicsmaths)
R u the new zacken btw. U seem to know everything bout maths
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 12082016 10:27
http://www.physicsandmathstutor.com/...02.pdf#page=36
Question and worked solution I'm stuck on in the link; I can't figure out how to do parts b and c.
My working:
a) as in worked solutions found that R (apq, a(p+q) )
b) gradient = 2/(p+q), insert (a, 0) into y=mx+c to get y(p+q) = 2x2a ; which is equivalent to the equation found in the worked solutions when considering that pq=1. Not sure how to get the locus of R being x=a from that.
c) No working done as not sure how to find a locus as in b.
What I'm specifically stuck on:
 How to find the locus equation in b and c.
 Why inserting the coordinates of P into y=mx+c seems to work in the worked solutions, but inserting (a, 0), which the chord PQ passes through, doesn't.
 Most importantly: why finding the equation of the chord PQ has anything to do with finding the locus of R. R doesn't lie upon PQ, so what is the link? This is the part I need to understand most to be able to complete anything in this chapter.
Any help would be very much appreciated, I've been stuck on this for a couple of days and not been able to move on with the chapter, and exhausted every possible avenue to try to understand it. This is in the Edexcel FP3 book btw, Chapter 2 Ex F. 
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 12082016 14:18
(Original post by karim_elo)
http://www.physicsandmathstutor.com/...02.pdf#page=36
Question and worked solution I'm stuck on in the link; I can't figure out how to do parts b and c.
My working:
a) as in worked solutions found that R (apq, a(p+q) )
b) gradient = 2/(p+q), insert (a, 0) into y=mx+c to get y(p+q) = 2x2a ; which is equivalent to the equation found in the worked solutions when considering that pq=1. Not sure how to get the locus of R being x=a from that.
c) No working done as not sure how to find a locus as in b.
What I'm specifically stuck on:
 How to find the locus equation in b and c.
 Why inserting the coordinates of P into y=mx+c seems to work in the worked solutions, but inserting (a, 0), which the chord PQ passes through, doesn't.
 Most importantly: why finding the equation of the chord PQ has anything to do with finding the locus of R. R doesn't lie upon PQ, so what is the link? This is the part I need to understand most to be able to complete anything in this chapter.
Any help would be very much appreciated, I've been stuck on this for a couple of days and not been able to move on with the chapter, and exhausted every possible avenue to try to understand it. This is in the Edexcel FP3 book btw, Chapter 2 Ex F.
For c, if the gradient is and we are given that in this case for a chosen p and q that the gradient is 2, then p + q = 1, Now you can see that in the R coordinates something happens rather similar to part b. Let me know if you get it or not. 
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 13082016 09:52
(Original post by AMarques)
So you got pq = 1, so that means if you put that into your R coordinates, you now get so as p and q vary, only the ycoordinate of R will change, and it's xcoordinate stays at a.
For c, if the gradient is and we are given that in this case for a chosen p and q that the gradient is 2, then p + q = 1, Now you can see that in the R coordinates something happens rather similar to part b. Let me know if you get it or not.
And one final question does that mean this is the 'standard' way to find loci (other than when the question involves parametric equations)? i.e. Find the general coordinates of the variable point in terms of the two variables, find a relationship/equation between the two variables, and so substitute that into your coordinates to find the locus? Just asking because I want to understand how to solve all locus problems individually rather than coming back on here to ask for each slightly different question.
Thanks for the help by the way! 
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 13082016 13:28
(Original post by karim_elo)
Ah yes, if p+q=1 then the y coordinate = a. So it seems the key thing here in finding loci is to find a relationship between p and q and then substitute that in to your general R coordinates, and finding the equation of the chord PQ is simply a vehicle to do that  just as using the gradient in part c is sufficient to do the same? I think that's what was puzzling me the most since I couldn't understand the relationship between PQ and R.
And one final question does that mean this is the 'standard' way to find loci (other than when the question involves parametric equations)? i.e. Find the general coordinates of the variable point in terms of the two variables, find a relationship/equation between the two variables, and so substitute that into your coordinates to find the locus? Just asking because I want to understand how to solve all locus problems individually rather than coming back on here to ask for each slightly different question.
Thanks for the help by the way!
In the FP3 chapter, you will need to familiarize yourself with simple trig identities (normally ). Sometimes the answer may be given, and it is sufficient to simply verify the result by plugging in the values of x and y (this is normally really hard loci questions, but they are still doable with trig identities).
For instance, say we found the coordinates of a point to be . The way I do it is I let . If we make and the subject, and take the square, we get and . We can then imply, using the trig identity, that .
I hope this made sense, and no problem. 
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 13082016 17:04
what c4 topics do i need in order to comlete fp2 as i have only done c3 and was wondering if that is neough to do fp2 or which topics will i need from c4

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 13082016 17:19
(Original post by youreanutter)
what c4 topics do i need in order to comlete fp2 as i have only done c3 and was wondering if that is neough to do fp2 or which topics will i need from c4 
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 13082016 17:22
(Original post by youreanutter)
what c4 topics do i need in order to comlete fp2 as i have only done c3 and was wondering if that is neough to do fp2 or which topics will i need from c4 
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 15082016 12:25
which applied module is quickest for most ppl to selfteach s3 d2 or m3
also does anyone have any good resources for s3 as wanted to take a better look 
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 15082016 12:26
(Original post by youreanutter)
which applied module is quickest for most ppl to selfteach s3 d2 or m3
also does anyone have any good resources for s3 as wanted to take a better look
Fo for S3 its super easy and quick.
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 15082016 13:26
Would you recommend that I finish off C4 vectors (the only topic which I haven't fully learnt) when I recap C4 over the rest of the summer in preparation for MAT? I know only C1 and C2 can come up in the MAT but the person who runs the MAT thread recommended learning C3/C4 as it improves mathematical dexterity.
I'm done recapping C3 and I'm up to recapping C4 binomial at the moment.Last edited by Palette; 15082016 at 13:27. 
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 16082016 14:06
Q2. I'm not sure about the last part, I've successfully done everything before it. These numerical methods with Euler are all over the place.
I've gotten:
but I'm pretty sure the last part of that is wrong. I'm confused.
Posted from TSR MobileLast edited by RDKGames; 16082016 at 14:09. 
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 16082016 18:00
(Original post by RDKGames)
Q2. I'm not sure about the last part, I've successfully done everything before it. These numerical methods with Euler are all over the place.
I've gotten:
but I'm pretty sure the last part of that is wrong. I'm confused.
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Note: we have found what was from the previous part.Last edited by AMarques; 16082016 at 18:01. 
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 16082016 18:14
(Original post by AMarques)
It's not , it should be as that is the ycoordinate estimate that we obtained from Euler's formula. Then you just plug both of them into f(x,y). Let me know what you get for a and b since I've done it.
Note: we have found what was from the previous part.
a=2, b=1?
Also: when carrying out Euler's improved method, is there any efficient way to do it? Drawing tables or working them out 1by1 is a bit tedious. 
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 16082016 18:17
(Original post by RDKGames)
Ah of course! Got too confused between all the y's there.
a=2, b=1?
Also: when carrying out Euler's improved method, is there any efficient way to do it? Drawing tables or working them out 1by1 is a bit tedious.
I've never had this topic in my syllabus but knew it from doing other exam boards to gain more practice for step, I just do it the tedious way. I'm not quite sure what you mean by tables. 
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 16082016 18:21
(Original post by AMarques)
Precisely.
I've never had this topic in my syllabus but knew it from doing other exam boards to gain more practice for step, I just do it the tedious way. I'm not quite sure what you mean by tables.
You can tabulate this with variables and work your way through the table. Take quite a while though but ensures accuracy.Last edited by RDKGames; 16082016 at 18:23. 
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 16082016 18:24
(Original post by RDKGames)
Ah okay. For table I'm referring to the version where and
You can tabulate this with variables and work your way through the table. Take quite a while though but ensures accuracy. 
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 16082016 22:00
Im not sure where to begin with this question as I don't understand what they're asking for, any hints? Q7
Posted from TSR MobileLast edited by RDKGames; 16082016 at 22:01. 
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 16082016 22:02
(Original post by RDKGames)
Im not sure where to begin with this question as I don't understand what they're asking for, any hints? Q7
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Updated: November 26, 2016
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