Question

Write the formula for the geometric sequence.
5, 10, 20, 40, …
A. an=40∙2n-1
B. an=40∙2n
C. an=5∙2n-1
D. an=5∙2n

Answer 1

Let \(n=1\) and see which ones still work.

Answer 2

So what does n represent? The number of the term. So n=1 for 5 since it's the first term. n=2 for 10, since it's the second.

an on the other hand represents the number itself, so a1=5, a2 represents 10. Of course, that's not multiplication, the n is the subscript just like the 1 and 2 I wrote next to the a, so don't confuse it.

Answer 3

So is the answer B?

Answer 4

@Kainui Use \(\LaTeX\)

Answer 5

is it B?

Answer 6

No

Answer 7

See for B\[
a_1=40^{2(1)}=40^2\neq 5
\]

Answer 8

than is it D?

Answer 9

\[
a_1=5^{2(1)}=5^2\neq 5
\]

Answer 10

Think about it.

Answer 11

@wio but I'm LAZEY

Answer 12

i dont know! :(