Mathematics: Post your doubts here!

[Serenia]

Hello!

Can you please please help me in this question of Pure Maths 3?

It is question 5. You can just give a brief outline of the solution. I was able to find the derivative of the function and equate it to zero. I got what is on the mark scheme, but from there I couldn't eliminate y to find an equation for x. I just need someone to tell me how to do it in words, I can do the rest.

Thanks. Any help is appreciated.

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_32.pdf
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_ms_32.pdf

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
Q6 (iv) why do we use 50.5 , 125.5 and so on as mid values ?! .. why did we add the 0.5 and from where It Came !?

Q7 fully

Thanks

ZaqZainab

 

[khaled talat]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_61.pdf
Q6 (iv) why do we use 50.5 , 125.5 and so on as mid values ?! .. why did we add the 0.5 and from where It Came !?

Q7 fully

Thanks

ZaqZainab

Q6(iv) will take the range from 0.5<x<100.5 and 100.5<x<150.5 and so on
Q7(a) (i) n=9 p=1/6 q=5/6
p(x>=1) = 1-(9C0 * 1/6^0 *5/6^9)
ii) 1-(5/6)^n <0.9 0.1<(5/6)^n Ln(0.1)<n*ln(5/6)
N>ln(0.1)/ln(5/6)
n>12.6 N=13
(B) if the 3rd one is yellow = 5/8 * 4/7 * 3/6 * 2/5 * 1/4 * 3/3
If the 2nd is yellow = 5/8 * 4/7 * 3/6 * 3/5
If the 1st is yellow = 5/8 * 3/7
Then add all of them

 

[moonangel996]

Q6(iv) will take the range from 0.5<x<100.5 and 100.5<x<150.5 and so on
Q7(a) (i) n=9 p=1/6 q=5/6
p(x>=1) = 1-(9C0 * 1/6^0 *5/6^9)
ii) 1-(5/6)^n <0.9 0.1<(5/6)^n Ln(0.1)<n*ln(5/6)
N>ln(0.1)/ln(5/6)e
n>12.6 N=13
(B) if the 3rd one is yellow = 5/8 * 4/7 * 3/6 * 2/5 * 1/4 * 3/3
If the 2nd is yellow = 5/8 * 4/7 * 3/6 * 3/5
If the 1st is yellow = 5/8 * 3/7
Then add all of them

Question 6 why the range will start from 0.5 ?? i mean why your adding 0.5 ???

 

[khaled talat]

Question 6 why the range will start from 0.5 ?? i mean why your adding 0.5 ???

Because in part iii) he said from 201 to 250 so there is a different of 1 between 200 and 201 so you have to subtract 0.5 from every lower no. And add 0.5 to every upper no.
(You will begin the first range from 1<x<100)

 

[Gehad Mohamed]

we have a total of 12 tress lets take tress other than hibiscus
so we have 8 tress
8! diffrenent arrangemnts
coming to the hibiscus tree 4 of them have 9 different places
so
9P4
Multiply them

Thanks alot Zainab

 

[Audrey J]

Dang, I'm freaking out. Please help http://onlineexamhelp.com/wp-content/uploads/2014/02/9709_w13_qp_31.pdf Q8 (a)

 

[MaRyy xD]

Help guys pleaseeeee.. I always stuck with argand stuff
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w13_qp_33.pdf
how do you solve Q9 part a??

 

[Beyond650]

Dang, I'm freaking out. Please help http://onlineexamhelp.com/wp-content/uploads/2014/02/9709_w13_qp_31.pdf Q8 (a)

http://i.imgur.com/U8a8wmp.jpg

You basically have to eliminate either u or v from the equations and solve simultaneously. You could have also solved it by eliminating u like:
u + 2v = 2i - the first equation
Making u the subject:
u = 2i - 2v - (1)
As the other equation given is :
iu + v = 3 - (2)
Substitute (1) into (2):
i(2i-2v) + v = 3
-2 -2iv + v = 3
v - 2iv = 5
Making v the subject
v(1-2i) = 5
v= 5/(1-2i) - this is the second form given in the mark scheme

Help guys pleaseeeee.. I always stuck with argand stuff
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w13_qp_33.pdf
how do you solve Q9 part a??

http://i.imgur.com/Ouotvyn.jpg

Edit: Er... if you were talking about graphing the argand diagrams question then it's lost on me too. Maybe these resources might help on graphing complex numbers in exponential form:
http://tutorial.math.lamar.edu/Extras/ComplexPrimer/Forms.aspx
http://www.intmath.com/complex-numbers/5-exponential-form.php
There are too many links; google "complex numbers +exponential form" for more resources

 

[moonangel996]

Because in part iii) he said from 201 to 250 so there is a different of 1 between 200 and 201 so you have to subtract 0.5 from every lower no. And add 0.5 to every upper no.
(You will begin the first range from 1<x<100)

okii can you check this one please ?? they subtracted 0.5 in Question3 (iii) here why ??? when do we subtract & when we add ?? i mean how do we know ??
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s11_qp_63.pdf
The mark scheme
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s11_ms_63.pdf
Thank you

 

[panoramafolks]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_31.pdf, Q:10, part i, please help me.

 

[panoramafolks]

Hello!

Can you please please help me in this question of Pure Maths 3?

It is question 5. You can just give a brief outline of the solution. I was able to find the derivative of the function and equate it to zero. I got what is on the mark scheme, but from there I couldn't eliminate y to find an equation for x. I just need someone to tell me how to do it in words, I can do the rest.

Thanks. Any help is appreciated.

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_32.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_ms_32.pdf

 

[Talha Irfan]

I need a genius to solve this equation :

[n(n-1)(n-2)] ÷ (n-4)! = 1

 

[Serenia]

Thank you so much. I really understood it.

 

[khaled talat]

okii can you check this one please ?? they subtracted 0.5 in Question3 (iii) here why ??? when do we subtract & when we add ?? i mean how do we know ??
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_63.pdf
The mark scheme
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_ms_63.pdf
Thank you

It is the same see part (ii) he says from 20 to 34 while the next one start from 35 so there is a different of 1

 

[syed1995]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w12_qp_33.pdf

Q10b

 

[panoramafolks]

Help guys pleaseeeee.. I always stuck with argand stuff
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w13_qp_33.pdf
how do you solve Q9 part a??

 

[Ahmed Aqdam]

I need a genius to solve this equation :

[n(n-1)(n-2)] ÷ (n-4)! = 1

As only 0! and 1!=1, n(n-1)(n-2) ÷ (n-4) will be equal to 0 or 1.
With an equation with zero you get n=1 or 2 and with 1 you get n=-0.89

 

[forget_me.not]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_31.pdf
Q.7 first part
please, anyone who can show me how to solve it.

 

[Champ101]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_31.pdf
Q.7 first part
please, anyone who can show me how to solve it.

you take w= a + ib and w* = a -ib and put these values in the equation, simplify it and you will get the answer!