Actually, there are TWO possible geometric means between the numbers x and 1/x.
One geometric mean between the numbers x and 1/x is the number 1.
Other geometric mean between the numbers x and 1/x is the number -1.
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| So, there are TWO POSSIBLE answers: 1 OR -1. |
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It will be good mental exercise for you to think and to understand WHY IT IS SO.