Question

Write an equation for the nth term of each geometric sequence: 1) 2,-6,18,… 2) 5,10,20,…

Answer 1

Answer:

see explanation

Step-by-step explanation:

The nth term of a geometric sequence is

$a_{n}$ = a₁ $r^{n-1}$

where a₁ is the first term and r the common ratio

(1)

a₁ = 2 and r = $\frac{a_{2} }{a_{1} }$ = $\frac{-6}{2}$ = - 3 , then

$a_{n}$ = 2 $-3)^{n-1}$

(2)

a₁ = 5 and r = $\frac{10}{5}$ = 2 , then

$a_{n}$ = 5 $(2)^{n-1}$