Mathematics: Post your doubts here!

[LindaKim123]

how do u do
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_33.pdf

whole question 10?

I tried i) and stuck when I got w^2= -3 +4i

 

[D0cEngi]

Guys plz help me out in the last three questions of this paper: http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_32.pdf

 

[D0cEngi]

N p! Just remember me in your prayers!

I will.

 

[farah3]

hiii pleaaaase anyone knows from where i can get maths and physics past paper 2013!! theyre gonna be my term exam :S
[email protected]

 

[WayneRooney10]

Tried ten to the best of my abilities!! I hope you can do part two now that one is cleared up

Awesome work man! But I do not understand the step where you substitute (cos2x)^2 by 1-sin^2x...Can anyone explain it to me?

 

[LMGD33]

how do u do
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_33.pdf

whole question 10?

I tried i) and stuck when I got w^2= -3 +4i

10i) u-w =4i ----1 and uw = 5--------2
u= 5/w
substitute this in eq 1
5/w -w =4i
5-w^2 = 4i
w^2 +4i -5 =0
w= -4i +/- √{(4i)^2 - 4*-5*1}
w= -41 +/- √(-16+ 20)
w = -4i +2/2 -4i-2/2
w= -2i+1 and -2i-1

u= 5/w
u= 5/1-2i
u= 5(1+2i) /4+1
u= 10i +5/5
u= 2i + 1
and it's conjugate u= 2i-1

ii) Sorry this is a little messy-View attachment 26656
The red shaded region is the answer for part ii

iii) I labeled the length of the real axis that represents the max ReZ
You know that the argument of Z is π/4
Cos π/4 = max ReZ/ √8 + 2
ReZ = 1/√2 * (√8+2)
ReZ= 2+ 2/√2

credit to littlecloud11

 

[LMGD33]

Awesome work man! But I do not understand the step where you substitute (cos2x)^2 by 1-sin^2x...Can anyone explain it to me?

Thanks
It's the first rule of trig, cos^2 + sin^2 = 1 , so cos^2 = 1- sin^2
Hope this helps!

 

[LindaKim123]

LMGD33 isn't part become 5-w^2 =4iw after 5/w-w = 4i?

 

[WayneRooney10]

Thanks
It's the first rule of trig, cos^2 + sin^2 = 1 , so cos^2 = 1- sin^2n
Hope this helps!

But you substituted (cos2x)^2, and not (cosx)^2? Right? Because (Cos2x)^3= (cos2x)^2 x (cos2x).

 

[LMGD33]

LMGD33 isn't part become 5-w^2 =4iw after 5/w-w = 4i?

Yes the OP forgot the w in the first few steps but it has no effect on the final answer, because w here is just like x in a quadratic eqn such as:
ax^2 + bx+c = 0
x = -b +- sqrt ( (b)^2 - 4 (a) (c) ) / 2a
So it doesn't have any effect, thanks for pointing it out!!

 

[LMGD33]

But you substituted (cos2x)^2, and not (cosx)^2? Right? Because (Cos2x)^3= (cos2x)^2 x (cos2x).

You're right, just apply the formula to the question at hand, sorry I wasn't clearer

 

[D0cEngi]

hiii pleaaaase anyone knows from where i can get maths and physics past paper 2013!! theyre gonna be my term exam :S
[email protected]

They will be available on this website after 3 months the May/June session has ended.

 

[LindaKim123]

Yes the OP forgot the w in the first few steps but it has no effect on the final answer, because w here is just like x in a quadratic eqn such as:
ax^2 + bx+c = 0
x = -b +- sqrt ( (b)^2 - 4 (a) (a) ) / 2a
So it doesn't have any effect, thanks for pointing it out!!

Oh!!! Okay! now I got it!! Thanks man! so cool!

 

[LindaKim123]

Another question!!
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w11_qp_31.pdf

question 10 b) finding the greatest value of arg z, how should I do it?

 

[SararaIH]

Hey everyone,
I know that there is a saying that you shoudn't work too much or put too much pressure on yourself before the day of your exam. But can anyone give me some tips and advice about what I should do before the day of the exam? Like revision methods or revision styles that should follow? Or what papers I should solve before the day of the exam?

 

[Ashique]

Hi, just wanted to clear something really simple about the iteration question. When the questions asks to show the result of each iteration to 4 decimal places, how would I present my work?
Like
T1=
T2=
T3=
T4=

And so on?

 

[Anika Raisa]

Please HELP!!
Hey can any1 tell me hw to integrate 4x/(4+x^2) ?

Thank u!!
SararaIH
PhyZac .... or any1?

 

[Anika Raisa]

Please HELP!!
Hey can any1 tell me hw to integrate 4x/(4+x^2) ?

Thank u!!
SararaIH
PhyZac .... or any1?

 

[LMGD33]

Hi, just wanted to clear something really simple about the iteration question. When the questions asks to show the result of each iteration to 4 decimal places, how would I present my work?
Like
T1=
T2=
T3=
T4=

And so on?

This is how I like to present it..

 

[Ashique]

Another question!!
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_31.pdf

question 10 b) finding the greatest value of arg z, how should I do it?

This question got to everyone. No one ever posted a solution in this thread! If someone could PLEASE solve it, I would be so grateful.
What I would recommend, however, is to draw it on a graph paper, and then use trigonometry.