Question

Write an equation for the nth term of the geometric sequence. Then find the 7th term. 2,-6,18,-54,...

Answer 1

soln,

from the series,

a = 2

t2 = -6

r = t2/a

`= ( - 6)/(2)`

= -3

therefore, tn =

`{ar}^(n - 1)`

`= {2 * - 3}^(n - 1)`

now,

seventh term =

`{2 * - 3}^(7 - 1)`

`= {2 * - 3}^(6)`

`= 2 * 729`

`= 1458`