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Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: EMO123 on February 05, 2011, 01:09:13 pm

Title: Binomial Theorem (P1) - doubt
Post by: EMO123 on February 05, 2011, 01:09:13 pm

Hey everyone. I am new here.

Doubt is :

Given that the expansion of (1 + ax)ⁿ begins 1 + 36x + 576x², find the values of a and n.

Thank you.

Title: Re: Binomial Theorem (P1) - doubt
Post by: EMO123 on February 06, 2011, 06:13:36 am

Is there anyone who can solve my doubt  :o

Title: Re: Binomial Theorem (P1) - doubt
Post by: Khey [Rainbow] on February 06, 2011, 04:28:46 pm

Hey EMO123

Here is the solution to ur query:
(1+ax)^n = 1+36x+576x^2
1+n(ax)+[n(n-1)(ax)^2]/2! = 1+36x+576x^2

na=36
n= 36/a  

subsitute 36/a for n
[36/a(36/a-1)a^2] divide by 2 factorial and this equals to 576
and u'll end up with an equation
(1296a-36a^2)/a=1152
36a^2+1152a-1296a=0
a(36a-144)=0
36a=144
a=4
n=36/4
n=9

HOPE THIS HELPS  ;)

Title: Re: Binomial Theorem (P1) - doubt
Post by: EMO123 on February 08, 2011, 02:47:43 pm

thanxx khey for your help

Title: Re: Binomial Theorem (P1) - doubt
Post by: Khey [Rainbow] on February 08, 2011, 03:49:46 pm

Anytym  ;D

Title: Re: Binomial Theorem (P1) - doubt
Post by: EMO123 on February 08, 2011, 03:54:12 pm

there is another question posted can u plz solve that to
thanxx for the ans

Title: Re: Binomial Theorem (P1) - doubt
Post by: astarmathsandphysics on February 09, 2011, 10:42:30 am

where is this other question

Title: Re: Binomial Theorem (P1) - doubt
Post by: Khey [Rainbow] on February 09, 2011, 11:58:29 am

Emo123
where is the other question???

Title: Re: Binomial Theorem (P1) - doubt
Post by: elemis on February 09, 2011, 01:05:07 pm

Quote from: Khey on February 09, 2011, 11:58:29 am

Emo123
where is the other question???

Its been solved.

Title: Re: Binomial Theorem (P1) - doubt
Post by: EMO123 on February 09, 2011, 02:10:09 pm

it is a new topic