Mathematics: Post your doubts here!

[Esme]

i^(1/2) = a + ib
i = (a + ib)^2
i = a^(2) + 2abi - b^(2)
a^(2) - b^(2) = 0 , 2ab = 1

solve them simultaneously

Oh yeah i just did it like this and got it

 

[Esme]

may be then its okay.. but i cant guarantee it ..

Ummm ok... so how would you do it ?

 

[MustafaMotani]

Ummm ok... so how would you do it ?

in this case i would have used somewhat similar values like 1 or 2 ...but there was one question in which i used pi/4 as initial value to get the answer .. (it ws a trig question) ..

 

[MustafaMotani]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_31.pdf

Can anybody please give me the solution to the whole of Q 6) , Q7 iv) and Q 10i

6
i)OM = (OA + OB)/2

AN = 2NC
ON-OA=2(OC-ON)
3ON = 2OC + OA
ON = (2OC + OA ) /3

once u get both .. it will be easy to get the equation ..

ii) find an equation of BC and just equate MN = BC to get the answer ( tell me if you want details)

 

[Esme]

Alice123

 

[MustafaMotani]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_31.pdf

Can anybody please give me the solution to the whole of Q 6) , Q7 iv) and Q 10i

this is what i got

 

[WayneRooney10]

cos4x - 4cos2x + 3
cos(2x+2x) - 4( 1- 2sin^2x) + 3
cos2xcos2x-sin2xsin2x -4 + 8sin^2x +3
(1-2sin^2x)^2 - (2sinxcosx)^2 + 8sin^2x -1
1-4sin^2x+4sin^4x - 4sin^2x(1-sin^2x) + 8sin^2x -1
4sin^2x + 4sin^4x - 4sin^2x + 4sin^4x
8sin^4x

I may have skipped a few steps but remember you have to replace all the cos with sin, wherever you can.

Woah! Thank you sooo much!

 

[AlishaK]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q8 i) I did the whole thing right but im messing up with the signs.
So please. Esme or PhyZac !!
Thanks!

 

[WayneRooney10]

http://papers.xtremepapers.com/CIE/...AS Level/Mathematics (9709)/9709_w08_qp_3.pdf
Q10 (iv). The solution doesn't make any sense to me :/ Please do explain the logic behind it. Thanks!

 

[SararaIH]

6
i)OM = (OA + OB)/2

AN = 2NC
ON-OA=2(OC-ON)
3ON = 2OC + OA
ON = (2OC + OA ) /3

once u get both .. it will be easy to get the equation ..

ii) find an equation of BC and just equate MN = BC to get the answer ( tell me if you want details)

Thank you so much The second part of the question is easy. I just didn't know how to get N and M.

 

[SararaIH]

this is what i got

I had also gotten the same thing except, I just didn't know where to shade.
Thanks so much!
Can you also kindly please show me how to do Q10i) of that same paper?

 

[LindaKim123]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w10_qp_31.pdf

Q 7 (iii) please!!!

 

[PhyZac]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q8 i) I did the whole thing right but im messing up with the signs.
So please. Esme or PhyZac !!
Thanks!

I did that yesterday.
See, you are not messing with sign
for i believe you got -10u above and down 6-u^2-u (i dot remember exactly)
to be honest, from this step, you could (i would) directly jump to the conclusion. which is the prove.

 

[MustafaMotani]

I had also gotten the same thing except, I just didn't know where to shade.
Thanks so much!
Can you also kindly please show
me how to do Q10i) of that same paper?

here yu go ..
u shuld know standard formulas for surface area and volume of spheres.

 

[MustafaMotani]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w10_qp_31.pdf

Q 7 (iii) please!!!

its simple OP is actually the normal to the required plane.. coaz it says that AB is on the plane and OP is perpendicular to the plane.

simply use
r.n = a.n ( take OA or OB in place of a)
(x,y,z) x (2/3,5/3,7/3) = (1,2,2) x (2/3,5/3,7/3)
2x + 5y + 7z = 26

 

[LindaKim123]

(x,y,z) x (2/3,5/3,7/3) = (1,2,2) x (2/3,5/3,7/3)
after here, how did u get
2x + 5y + 7z = 26?

I'm sorry but can u go in more detail?

 

[LindaKim123]

Ohh!!!

I got it!!!

Thank you so much! @MustafaMotani

 

[MustafaMotani]

(x,y,z) x (2/3,5/3,7/3) = (1,2,2) x (2/3,5/3,7/3)
after here, how did u get
2x + 5y + 7z = 26?

I'm sorry but can u go in more detail?

I simply dot them .. dat is what yu do ..

 

[MustafaMotani]

Ohh!!!

I got it!!!

Thank you so much! @MustafaMotani

oh gud..

 

[AlishaK]

I did that yesterday.
See, you are not messing with sign
for i believe you got -10u above and down 6-u^2-u (i dot remember exactly)
to be honest, from this step, you could (i would) directly jump to the conclusion. which is the prove.

thanks i kinda got it thou.
See, when u find the limits, for x=5 u get 1 and for x=2 u u get 2. the upper limit is lesser than the lower so we gotta flip it that is why we multiply by -1 while integrating. (write -1 bfore the integ sign)