# Mathematics: Post your doubts here!

Discussion in 'International A And AS Level' started by XPFMember, Sep 8, 2011.

Messages:
270
1
Trophy Points:
28
Gender:
Male
1357913579 thanx alot....=)

2. ### XPC Bot

Messages:
270
1
Trophy Points:
28
Gender:
Male
Same here....

Messages:
270
1
Trophy Points:
28
Gender:
Male
Solve thz Identity:

( 1/sinx - 1/tanx )^2 = 1-cosx/1+cosx

5. ### 1357913579

Messages:
467
102
Trophy Points:
53
Gender:
Male
Location:
saudi arabia
are you giving statistics in this november

6. ### Silent Hunter

Messages:
4,609
3,907
Trophy Points:
323
me?

Messages:
270
1
Trophy Points:
28
Gender:
Male
me?

8. ### sagystu

Messages:
148
13
Trophy Points:
28
9. ### Silent Hunter

Messages:
4,609
3,907
Trophy Points:
323
well if ur asking from me............i am not giving the paper of stats ... AS maths + stats in 2012 june........

NEED HELP IN PERMUTATIONS AND COMBINATIONS!!!!

10. ### XPFMemberXPC ModeratorStaff Member

Messages:
4,540
13,233
Trophy Points:
523
Assalamoalaikum!!

For permutations and combinations watch this whole series of the tutorial, and you're good to go! http://www.examsolutions.co.uk/maths-re ... rial-1.php

I see people finding permutations and combinations hard, but honestly i enjoy it a lot..

And one more thing, (you may understand this better may be after you've gone through the topic, but anyways)
to make out when you have to use permutation (nPr of the calculator) and when to use combinations (nCr) , checck if the different arrangements of the selections will make any difference or not...if it does then you've to use nPr, and if it doesn't then u must use nCr.

Eg. lets say I want to choose two numbers from a total of three..how many possible selections are there?

now see i may choose 1 2 ; 1 3 ; 2 3
now the no. i've chosen can be written as 2 1 ; 3 1 ; 3 2

and obviously, this is giving me different numbers, so here arrangement does matter..so go for nPr => 3P2 = 6

but say if i got to chose 2 people from a total of 3 (A, B and C)

so possibilities are A B ; A C ; B/ C
and if i make this as B A ; C A ; C B
it doesn't make any difference as in the end there are the same people whether A first or B first....so that means arrangement does not matter...we'll use nCr => 3C2 = 3

P.S. These were pretty simple examples, I used them to explain the concept...you'll find this part of my explanation helpful when later on you tackle some more harder situations...this part really makes this thing easy...it did for me

11. ### nikhil000

Messages:
67
1
Trophy Points:
8
Gender:
Male
Location:
Kathmandu ,nepal
Anyone out there ..Plz help me!

12. ### XPFMemberXPC ModeratorStaff Member

Messages:
4,540
13,233
Trophy Points:
523
Assalamoalaikum..

Check this:

File size:
23.1 KB
Views:
266
13. ### sagystu

Messages:
148
13
Trophy Points:
28
14. ### NehaKush

Messages:
50
3
Trophy Points:
8
which question?

15. ### NehaKush

Messages:
50
3
Trophy Points:
8
i nid notes on vectors paper3.. thnx

16. ### mrpaudel

Messages:
502
8
Trophy Points:
28
Gender:
Male
Location:
Kathmandu, Nepal

I hope this will help...!! but a bit messy...sorry for that..!!

File size:
80.7 KB
Views:
141
17. ### IgoforA

Messages:
105
0
Trophy Points:
0

File size:
39.1 KB
Views:
114
18. ### mrpaudel

Messages:
502
8
Trophy Points:
28
Gender:
Male
Location:
Kathmandu, Nepal

File size:
100 KB
Views:
110
19. ### XPFMemberXPC ModeratorStaff Member

Messages:
4,540
13,233
Trophy Points:
523
20. ### mrpaudel

Messages:
502
8
Trophy Points:
28
Gender:
Male
Location:
Kathmandu, Nepal
m lazy one..so wrote it in degree...u have to write it in radian from the very first...!! i think u know it....anyways..!! i hope it helped..!!

21. ### mrpaudel

Messages:
502
8
Trophy Points:
28
Gender:
Male
Location:
Kathmandu, Nepal

File size:
92 KB
Views:
114