Geometric sequence is 3/2, -3/4, and 3/8 are the first three terms. what represents the nth term of the sequence?

I know a is the first term, 3/2.

ratio is just a term divided by the term proceeding it.

ar^(n-1) is how you find a specific term.

I get all the way up to here: a(n) = ar^(n-1) = (3/2)(-1/2)^(n-1)

the final answer the book says, and this website I got help from: http://www.algebra.com/algebra/homew...on.391759.html

says the final answer is:

a(n) = 3*(-1)^(n-1)/2^(n)

My question is, what happens to the other 2 in the denominator, and where does that n exponent in the denominator come from?

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