Answer: The missing term in the given geometric sequence is 20√5 or -20√5.
Step-by-step explanation: We are given to find the missing term in the following geometric sequence :
4, ?, 500, . . .
Let b represents the missing term.
Since the given sequence is a geometric one, so there common ratio r such that

Thus, the missing term in the given geometric sequence is 20√5 or -20√5.