Question

Find the first 5 terms of each sequence.
An=1/2an-1, where a1= 20

Answer 1

Do you do connections academy?

Answer 2

Hmm, what's the difference or ratio? I'm not familiar with what an-1 is

Answer 3

yes, I do.
& That's all the problem gave me. I have no clue how to do it.

Answer 4

\(\bf \Large a_{\color{red}{ n}}=\cfrac{1}{2}a_{{\color{red}{ n}}-1}\qquad \qquad a_1=20\)

Answer 5

\(\Large \bf a_{\color{red}{ 5}}=\cfrac{1}{2}a_{{\color{red}{ 5}}-1}\implies a_{\color{red}{ 5}}=\cfrac{1}{2}a_{{\color{red}{ 4}}}\)

Answer 6

Ohh, thats the formula they want you to use, plug in 5 for n,

a_5 = 1/2*5-1 = a_5 = 1/2*a4

Answer 7

I do connections as well. I remember this question but not the answer sorry :(

Answer 8

the next term is dependent on the previous term
so you'd need to find the 4th to get the 5th
and the 3rd to get the 4th and so on

your starting point is of course \(\bf a_1=20\)

Answer 9

well.... actually no quite... you don't have to...

Answer 10

\(\bf \Large a_{\color{red}{ n}}=a_1\cdot r^{{\color{red}{ n}}-1}\qquad r=\textit{common ratio}=\cfrac{1}{2}\)

Answer 11

recall -> http://www.mathsisfun.com/algebra/sequences-sums-geometric.html the geometric sequence equation to find the "nth" term

Answer 12

so then The 5 terms would be?