Answer
missing term = $\pm 6$
Work Step by Step
The middle term of three consecutive terms of a geometric sequence can be found using the geometric mean formula:
geometric mean = $\sqrt {3 \bullet 12}$
Multiply terms within the radicand first:
geometric mean = $\sqrt {36}$
Take the square root:
geometric mean = $6$
The missing term could be either the geometric mean or its opposite, so we need to include both positive and negative values:
missing term = $\pm 6$
