Question #944c9

2 Answers
Jul 1, 2017

#a_(n) = (- 3)^(n - 1)#

Explanation:

The given sequence #(1, - 3, 9, -27, ...)# is a geometric sequence with a common ratio of #- 3#.

The general term of any geometric sequence is in the form #a_(n) = a_(1) r^(n - 1)#; where #a_(n)# is the #n#th term, #a_(1)# is the first term, #r# is the common ratio, and #n# is the term number.

Using this information, let's form an expression for the general term of the given sequence:

#Rightarrow a_(n) = 1 cdot (- 3)^(n - 1)#

#therefore a_(n) = (- 3)^(n - 1)#

Therefore, the answer you came up with was correct.

Jul 1, 2017

#(-1)^(n-1)xx3^(n-1)#

Explanation:

The answer below or the other one was correct however I learned to do it a differenet way. I would write the negative sign in a different equation

#(-1)^(n-1)xx3^(n-1)#

I hope that helped you a little.