IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Math => Topic started by: vids on May 17, 2009, 04:20:20 pm

Title: sequences
Post by: vids on May 17, 2009, 04:20:20 pm

hey cn any1 tell m d formulae to find out d nth term
please nidhi help

Title: Re: sequences
Post by: vids on May 17, 2009, 04:25:22 pm

i just knw dis1
a+(n-1)d

Title: Re: sequences
Post by: EGY_Voldmort on May 17, 2009, 04:31:12 pm

Un = a+(n-1)d

n : order
a : 1st number
d : difference

Title: Re: sequences
Post by: junky demon on May 17, 2009, 04:31:41 pm

for eg.if the no.z r 1,4,9,16...
then yu keep findin the diff. until it reaches a single no. btween ol..tht is for the first one:3,second:5,third:7 then the sme thin amongst the three no.z..wen lastly ull reach to 1..therefore  1n and raise to the no. of tyms u found the diff.exclude the tym wen u gt 1...so the ans is 1n^2...hope this helps and there is no easy way except the above formula for help at sequences..:D

Title: Re: sequences
Post by: vids on May 17, 2009, 04:32:04 pm

if d difference is not same den??

Title: Re: sequences
Post by: nid404 on May 17, 2009, 04:37:53 pm

i thought i told u the other day at school.
it's a+(n-1)d+(n-1)(n-2)c

a=first term
c= final difference
d=the difference between values of first and second term
 
got it ?

Title: Re: sequences
Post by: vids on May 17, 2009, 04:39:41 pm

Thanks..i forgot it
nyways...getting tensed

Title: Re: sequences
Post by: nid404 on May 17, 2009, 04:40:40 pm

relax...no1's eatin u up. anyways i gotta go.
Good Night

Title: Re: sequences
Post by: vids on May 17, 2009, 04:41:31 pm

night

Title: Re: sequences
Post by: EGY_Voldmort on May 17, 2009, 04:45:49 pm

Thanks for addition and wish us all good luck  :D

Title: Re: sequences
Post by: vids on May 17, 2009, 04:47:31 pm

al d best guys...

Title: Re: sequences
Post by: AN10 on May 17, 2009, 04:57:21 pm

hey can anybody tell me wht does c mean....final difference of wht??

Title: Re: sequences
Post by: EGY_Voldmort on May 17, 2009, 05:02:03 pm

yup final difference

Title: Re: sequences
Post by: AN10 on May 17, 2009, 05:05:16 pm

no i meant different of which two values ???

Title: Re: sequences
Post by: zara on May 17, 2009, 05:09:50 pm

"c" means difference of the difference

Title: Re: sequences
Post by: zara on May 17, 2009, 05:12:26 pm

Quote from: nid404 on May 17, 2009, 04:37:53 pm

i thought i told u the other day at school.
it's a+(n-1)d+(n-1)(n-2)c

a=first term
c= final difference
d=the difference between values of first and second term
 
got it ?

i think u 4got to add 1/2 in the formula...
its:  a + (n - 1)d + ½(n - 1)(n - 2)c

Title: Re: sequences
Post by: nid404 on May 17, 2009, 05:44:45 pm

ur right. i'm soooooooo sorry guys.....just forgot the half.

Title: Re: sequences
Post by: Ghost Of Highbury on May 17, 2009, 05:46:18 pm

@zara and nid404....
tks a lot...!!
appreciated

Title: Re: sequences
Post by: X Abdulrahman X on May 17, 2009, 07:11:37 pm

here u go,
http://www.s-cool.co.uk/gcse/maths/sequences/the-nth-term.html

gl  :)

Title: Re: sequences
Post by: AN10 on May 17, 2009, 08:02:37 pm

yeah i got it!!
thanx.... this was pretty helpful  ;D

Title: Re: sequences
Post by: X Abdulrahman X on May 17, 2009, 09:04:58 pm

Quote from: AN10 on May 17, 2009, 08:02:37 pm

yeah i got it!!
thanx.... this was pretty helpful  ;D

Your welcome  :)