Answer
$\pm 1530$
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 = $\sqrt {9180 \bullet 255}$
Multiply terms within the radicand first:
geometric mean = $\sqrt {2,340,900}$
Take the square root:
geometric mean = $1530$
The missing term could be either the geometric mean or its opposite, so we need to include both positive and negative values:
missing term = $\pm 1530$