Question

Find the ninth term of the

geometric sequence, given the
first term and common ratio.
a1=1 and r=-1/3

Answer 1

1(-1/3)^8

Answer: 1/6561

Explanation:

Answer 2

Explanation:

n th term = a ( r^(n-1) - 1)/ (r-1)

Ninth term = 1 * [ (-1/3)⁸ - 1 ] / (-1/3 -1)

= (1/6561) -1 / ( -1 -3/3) = [(1 - 6561) / 6561] / [-4/3]

= [-6560/6561] / -4/3

= -6560 * 3 / 6561 * -4

= 1640 / 2187