After an hour, it was found that
there were 9 bacteria in a test
tube. Accordingly,
these
bacteria triple (x3) every hour.
a. Illustrate the geometric
sequence with the first
three terms.
b. Determine the sum of the
first 8 terms in the
geometric sequence.​


Sagot :

Answer:

Given: a1=9, r=3

Formula: an=ar^n-1

a. ↓↓↓

> a3=(9)(3)^3-1

> a3=(9)(3)^2

> a3=(9)(9)

> a3=81

b. ↓↓↓

Formula: Sn=(1-r^n)/1-r

> S8=(1-(3)^8)/1-3

> S8=(1-6561)/2

> S8=6560/2

> S8=3280