PLEASE HELP QUICKLY WILL GIVE A MEDAL
Find an explicit rule for the nth term of a geometric sequence where the second and fifth terms are 36 and 2304, respectively

Question

PLEASE HELP QUICKLY WILL GIVE A MEDAL
Find an explicit rule for the nth term of a geometric sequence where the second and fifth terms are 36 and 2304, respectively

anonymous · Answer

@Directrix

directrix · Answer

Choices 

an = 9 ⋅ 4n+1 

 an = 9 ⋅ 4n+3 

 an = 9 ⋅ 4n-1 

 an = 9 ⋅ 4n-2

directrix · Answer

Courtesey of @pinterestaddict15 

Since 
 T(n)=T(1)r^(n-1) 
 => 
 T(1)r=36--------(1) 
 T(1)r^4=2304--------(2) 
 (2)/(1)=> 
 r^3=2304/36=> 
 r=4 
 From (1), get 
 T(1)*4=36=> 
 T(1)=9 
 => 
 the general term 
 T(n)=9*4^(n-1)

directrix · Answer

@faariat   You are welcome.