Respuesta :
I took it, and assuming I'm reading your question right, it's D: an=2/3*9^n-1
The Information about Geometric sequence is:
[tex]a_{1}=23 , a_{n}=9\times a_{n-1}[/tex]
→nth term of sequence = 9× (n-1) th term
Also , Common Ratio of a Geometric Sequence =[tex]\frac{\text{Second term }}{\text{First term}}[/tex]
[tex]\frac{a_{n}}{a_{n-1}}= \text{Common ratio}}=9\\a_{n}= a_{1}\times r ^{n-1}\\\\a_{n}=23\times 9^{n-1}[/tex]
Option 4 : [tex]a_{n}= 23 \times 9^{n-1}[/tex] is true.