please explain how you would go about doing this..
find the sixth term of a geometric sequence with t(5)=24 and t(8)=3.

Question

please explain how you would go about doing this.. 	
find the sixth term of a geometric sequence with t(5)=24 and t(8)=3.

hartnn · Answer

know the formula for n'th term?

anonymous · Answer

that's the t(n)t(1)r(-1) right?

anonymous · Answer

but I don't know the first term, otherwise it's easy for me

hartnn · Answer

use that formula for t5

t5 = 24
n=5

$24 =t_1r^4$

similarly use it for t(8) too

hartnn · Answer

$\Large 8= t_1r^7$

do u get this?

anonymous · Answer

no I don't understand that at all. what is the r and how did you get the 7 and the 4 for it? is it just the term minus 1?

hartnn · Answer

$t_n= t_1r^{n-1}$

for 8th term
n=8
t8 is given as 3

$\Large 3= t_1 r^{8-1}$
$\Large 3= t_1 r^{7}$

now?

anonymous · Answer

ok yeah, how will you find the first term?

hartnn · Answer

$21=t_1r^4 \ 8=t_1r^7$

divide these 2 equations!
and you will get 'r' 
(you need r also)

hartnn · Answer

24
not 21

anonymous · Answer

you mean divide 24 and 8?

hartnn · Answer

yep

anonymous · Answer

so 3. is that the first term or r?

hartnn · Answer

you divide both sides, isn't it ?
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