Question

math 12 geometric sequences.
which term has the value of 7over1024 in the geometric sequence 28,14,7

Answer 1

It's like before; find the common ratio first..
\[\large \frac{T_{2}}{T_{1}} = \frac{14}{28} = \frac{1}{2} \]
\[\large \frac{T_{3}}{T_{2}} = \frac{7}{14}=\frac{1}{2} \]

Then use the formula..
\[\large T_n = ar ^{n-1}\]
where a is the first term of the sequence and r is the common ratio..
\[\large T_n = \frac{7}{1024} \]
\[\large ar ^{n-1} = \frac{7}{1024} \]

Answer 2

yes I did that and i got
7 over 1024 = 28(1over2)to the power of n - 1

Answer 3

and i divided each sides by 28

Answer 4

and i used log method and I am not getting a right answer..

Answer 5

\[(n-1) \log(\frac{1}{2}) = \log(\frac{7}{1024*28})\]
\[n-1 = 12\]
n = 13

Answer 6

ohhhhh okay thanks!!! :)