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Mathematics: Post your doubts here!

Anika Raisa

Anika Raisa

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Hey SararaIH

Here is the soln to 6 i ... ar hah xcuse ma handwriting.... :D :cautious:

GEDC8091.JPG
SararaIH said:
I don't understand one thing. I mean, how do you know which value of x is the correct value? Because even if I take x=2, I get a negative value of -21.
And even if I take x=5, I get a positive value of 72. So how do I know which value of x to consider? :(
Click to expand...
 
LMGD33

LMGD33

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Hello guys, long time lurker, first time poster! You've all been a lot of help to me, this year and last year, and I really appreciate you taking time to help all of us!
Though, I never run out of questions, especially this year, I'm a private candidate with no teacher >.<
Could someone help with question 6 please? I got the dy/dx = 3cos(x) - 12 sin(x)cos^2(x) I just don't really know how to simplify it further..
Also question 5, I got stuck on this step : -e^(-y) = 1/2 e(2x) - 3/2
How can I ln it correctly?
Link: http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_32.pdf
Thanks in advance! And may God bless you all!

UPDATE : SOLVED CORRECTLY ( thanks sister :p ) WILL HELP IF NEEDED
 
Anika Raisa

Anika Raisa

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Twinks05 said:
Can anyone please explain to me how to solve question number 3 II part b from may/june 2012, paper 31
the link to the qp is here:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_31.pdf

The mark scheme link is here:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_ms_31.pdf

Please&Thankyou
Click to expand...

See over here the factor of p(x)=p(x^2)
So wat u do is root all the values of x u get for p(x)

Hope that helped!
 
Alice123

Alice123

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Jiyad Ahsan said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf

Q10 (iii) pleeeeeeease.. what the hell is going on in this question?
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Chem champ having prob with maths??? :p
Here u go.... This was done by Physac
We have to find the point p where the perpendicular distance to the two planes is same.


first we will for an equation the way the paper gave.
therefore
for plane m
|x+2y-2z-1|/sqrt((1^2) + (2^2) + (-2^2) = |x+2y-2z-1|/3 [P.S, sqrt is square root]
for plane n
|2x-2y+z-7|/sqrt((2^2)+(-2^2)+(1^2) = |2x-2y+z-7|/3


since you are finding a point where both distance is same , therefore.
|x+2y-2z-1|/3 = |2x-2y+z-7|/3 (3 can be cancelled both sides)
=
|x+2y-2z-1| = |2x-2y+z-7|

now we will sub the line values in the equation.
the x component (1+2t) [P.S, t is lamda ]
the y comp. (1+t)
the z comp. (-1+2t)

therefore.
| (1+2t) +2 ( 1+t) -2(-1+2t) -1 | = |2(1+2t) - 2(1+t) + (-1+2t) - 7 |
simplifying it you get
|4| = |-8+4t|
now to solve modulus, we do squaring method
16 = 64-64t+16t^2
simplify
2 = 8 - 8t +2t^2
2t^2 - 8t + 6 = 0
solve it and get
t = 3 or t= 1
when t=3 the position of point is [P.S, u do this by sub t value in line equation)
(7, 4, 5) => OA
when t = 1 the position of point is
(3, 2, 1) => OB

BA (or AB, same thing) = OA - OB
= (4 , 2, 4)

now find the mod
sqrt(4^2 + 2^2 + 4^2)
= 6
ask if u dont get
 
LMGD33

LMGD33

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Jiyad Ahsan said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf

Q10 (iii) pleeeeeeease.. what the hell is going on in this question?
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Lamda will be denoted as t
You know that P is a point on L , so it has x,y,z coordinates as follows : (1 + 2t), (1 + t), (-1 + 2t) , and m = x + 2y -2z = 1 and n = 2x - 2y + z = 7
Using the formula they provided, you find the distance of P to m and of P to n keeping in mind that they should be equal, so distance of P to m
| (1 + 2t) + 2 (1 +t) -2(-1 + 2t) - 1 | / square root ( 1^2 + 2^2 + (-2)^2 ) to get |4|/3
distance of P to n using the same equation will get you |4t - 8|/3
These two answers are equal, their numerators are equal so you square both sides to get rid of the modulus, leaving you with an equation such as :
4^2 = (4t - 8)^2
16 = 16t^2 - 64t - 64, solve for t and obtain t = 3 or t =1
substitute those two value in the original coordinates of P to get the two position vectors that are (7i + 4j + 5k) and (3i +2j + k) and then find the distance between these two points using your skill from P1! Good luck!
 
SararaIH

SararaIH

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Anika Raisa said:
Its ok ... i get blank on em 2! n pls stop being formal!!!

Between heres the one i ws tokin abt:
Question + Ms:
View attachment 26591


Bhumika's work

View attachment 26595

My work:

View attachment 26596

SararaIH
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Okay, I was also actually stuck in the same question but someone who has also been participating in this thread had offered to help me out. Unfortunately, for me and my silly brain, I can't quite remember who had helped me (n) So please forgive me if you are reading this right now, anonymous helper.
But I have saved the picture he/she had sent me of the solution to this question
I'll attach the solution here.
https://www.xtremepapers.com/community/attachments/w_12_qp33-q4-jpg.26305/
 
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