Notice that this is a geometric sequence because here we have equal common ratio.
So, common ratio : [tex] r = \frac{a_{2}}{a_{1}} [/tex]
= [tex] \frac{18}{54} [/tex]
= [tex] \frac{1}{3} [/tex]
The formula for general term of a geometric sequence is,
[tex] a_{n} =a_{1} r^{n-1} [/tex]
Where, first term: a_{1} =54.
Next step is to plug in the value of a1 and r in the above formula to get the formula of the given sequence. So,
[tex] a_{n} =54*(\frac{1}{3})^{n-1} [/tex]
Hope that helps you!
