Question

For the geometric sequence -8,16,-32.....find a5

Answer 1

start by finding \(r\)

Answer 2

how do i do thatt

Answer 3

divide any 'next element' with 'present element'

Answer 4

\(r = \frac{16}{-8}\)

Answer 5

is -2

Answer 6

than -32/16?

Answer 7

Yes, \(r = -2\)

Answer 8

Now use the \(nth\) term formula to find \(a_5\)

Answer 9

the 9th term? i only see 3 terms

Answer 10

\(\large a_n = ar^{n-1}\)

Answer 11

plugin n = 5, r = -2

Answer 12

\(\large a_5 = -8 (-2)^{5-1}\)

Answer 13

simplify

Answer 14

64?

Answer 15

\(\large a_5 = -8 (-2)^{4}\)

\(\large \ \ \ = -8 \times 16\)

Answer 16

lol oh -128

Answer 17

Yes