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

$= \frac{ - 6}{2}$

= -3

therefore, tn =

${ar}^{n - 1}$

$= {2 \times - 3}^{n - 1}$

now,

seventh term =

${2 \times - 3}^{7 - 1}$

$= {2 \times - 3}^{6}$

$= 2 \times 729$

$= 1458$