Question

Find an equation for the nth term of the sequence.

-4, -16, -64, -256, ...

Answer 1

The common ratio is \(\large\color{blue}{a_n \div a_{n-1} }\)

Answer 2

\(\large\color{blue}{a_n=a_{1} \times r^{n-1}}\) is the form

Answer 3

well each term is being multiplied by 4

so the sequence is geometric... and a term in a geometric series is

\[a_{n} = a \times r^{n - 1}\]

you know a = -4 and n = 4

so just substitute them

Answer 4

No, n is not 4, he is asking for any nth term in general, as I see.

Answer 5

an=-4*4^n-1

Answer 6

4^(n-1) is not the same as 4^n-1

Answer 7

oh, ok thanks

Answer 8

yeah, just marking that, np

Answer 9

making a new question, can you guys hop over?