Question

What’s the explicit formula for -4, -16, -64, -256

Answer 1

Answer:

$a_{n}$ = - 4$(4)^{n-1}$

Step-by-step explanation:

Note the common ratio r between consecutive terms in the sequence, that is

- 16 ÷ - 4 = - 64 ÷ - 16 = - 256 ÷ - 64 = 4

This indicates the sequence is geometric with n th term ( explicit formula )

$a_{n}$ = a$(r)^{n-1}$

where a is the first term and r the common ratio

Here a = - 4 and r = 4, thus

$a_{n}$ = - 4 $(4)^{n-1}$ ← explicit formula