Edexcel FP3 June 2015 - Official Thread Watch

chemlover12
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#441
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#441
(Original post by nayilgervinho)
The mark scheme said something different, could you do it?
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mdemda
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#442
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Once more, if it is possible, can someone explain, why, if we have transformation and plane in vector notation, and we need to find normal to transformed plane, we first cannot find normal to plane and then transform it?

I got ninjasinjps explanation, but I always thought that angle between lines is conserved in linear transformation.
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Pri2506
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(Original post by ninjasinpjs)
Hey bud, that was a very challenging question because of the trigonometry stuff, however the concepts are true if you keep to them you can do the question.

1) Find the gradient between the two points
2) Use the equation of the line
3) Use algebra manipulation by the factor formula in the c3 section of the book [ this is the tricky part]
4) Sub the factor formula into the question of your line, and then at the very last part apply double angle formula HINT [ Cos ( a - b) formula is used]

Hope this helps
Thank you!
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chemlover12
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#444
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#444
(Original post by nayilgervinho)
The mark scheme said something different, could you do it?

Finally. 2nd part
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ninjasinpjs
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(Original post by 13 1 20 8 42)
As the denominator gets smaller x gets larger; thus the largest denominator (in terms of magnitude) gives the smallest magnitude x values, hence |x| >/= a rather than the other way round
I do not understand, why lxl >/= a, i think i do not understand because of the modulus notation, ill assume that is means x >/= a and x</= -a.

The smallest value of the denominator is +/- 1, oh i SEEEEE, so if you got to 0.5, then x is larger than a. Can't believe i missed this point, thanks bud
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bwr19
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#446
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Sorry to keep asking questions guys, but what on earth has happened in these two stages (highlighted) for this reduction formula? I can see where the nIn-1 comes from, but how've they managed to get out 2nIn from all that?

Thanks!

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ninjasinpjs
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(Original post by bwr19)
Sorry to keep asking questions guys, but what on earth has happened in these two stages (highlighted) for this reduction formula? I can see where the nIn-1 comes from, but how've they managed to get out 2nIn from all that?

Thanks!

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By parts and some algebra, did you want help with the algebra?


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bwr19
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(Original post by ninjasinpjs)
By parts and some algebra, did you want help with the algebra?


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Well basically I've got this:

\displaymode 5^n \times 3 - 1 - \int^5_1 nx^{n-1} (2x-1)(2x-1)^{-\frac{1}{2}} dx

But where do I go from there? Any help is much appreciated!

I can see how they got the nIn-1 out of there, but how did they work with n(2x-1) to make it 2nIn?
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luckystar1900
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#449
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#449
Can anyone help me out on part b of Q57 on review excersise 1 in the edexcel book?? Like seriously how is anyone meant to think of that I am very confused
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Boop.
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#450
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Hey has anyone done June 2013 Question 2a, why do they multiply the answer by 0.5 after they have used the formula?
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math42
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(Original post by Boop.)
Hey has anyone done June 2013 Question 2a, why do they multiply the answer by 0.5 after they have used the formula?
The formula is for x^2, in this case you have (2x)^2, you need to multiply by a half as when you differentiate you get an extra 2 from the chain rule if that makes sense..try differentiating to convince yourself of this
This is true in general; if it was like 1/root(16x^2 +9) your integral would be (1/4)arsinh(4x/3) for instance
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chemlover12
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(Original post by bwr19)
Well basically I've got this:

\displaymode 5^n \times 3 - 1 - \int^5_1 nx^{n-1} (2x-1)(2x-1)^{-\frac{1}{2}} dx

But where do I go from there? Any help is much appreciated!

I can see how they got the nIn-1 out of there, but how did they work with n(2x-1) to make it 2nIn?
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Boop.
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(Original post by 13 1 20 8 42)
The formula is for x^2, in this case you have (2x)^2, you need to multiply by a half as when you differentiate you get an extra 2 from the chain rule if that makes sense..try differentiating to convince yourself of this
This is true in general; if it was like 1/root(16x^2 +9) your integral would be (1/4)arsinh(4x/3) for instance
Thanks mate
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Hazllye
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#454
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Hi can anyone help with question 5a from the June 2013 paper please?
I'm stuck with how to use the j+k and i-k in the eigen vectors and where they've got the (0,1,1) and (1,0,-1) column vectors from on the mark scheme

mark scheme https://3a14597dd5c7aa2363f067571766...%20Edexcel.pdf
paper
https://3a14597dd5c7aa2363f067571766...%20Edexcel.pdf
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math42
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(Original post by Hazllye)
Hi can anyone help with question 5a from the June 2013 paper please?
I'm stuck with how to use the j+k and i-k in the eigen vectors and where they've got the (0,1,1) and (1,0,-1) column vectors from on the mark scheme

mark scheme https://3a14597dd5c7aa2363f067571766...%20Edexcel.pdf
paper
https://3a14597dd5c7aa2363f067571766...%20Edexcel.pdf
Those vectors are just j + k and i - k in column vector form
You want to use the relationship Ax = lambda(x) with A the matrix, x the eigenvector and lambda the eigenvalue
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physicsmaths
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Literally just started fp3 revision now. The vectors are very fun and interesting.


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ninjasinpjs
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(Original post by physicsmaths)
Literally just started fp3 revision now. The vectors are very fun and interesting.


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😊


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xyzmaster
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(Original post by physicsmaths)
Literally just started fp3 revision now. The vectors are very fun and interesting
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After STEP this should be a walk in the park for you
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chughes17
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If it asks for a matrix's transformation in words, how do we know what this is?


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physicsmaths
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(Original post by xyzmaster)
After STEP this should be a walk in the park for you
Tbh. Seems like it. Sorry if this comes off as arrogant i dont mean it to be.


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