Geometric Mean
Recall that in the proportion
,
and are called the means , and and are called the extremes .
When the means of a proportion are the same number, that number is called the geometric mean of the extremes.
So if
,
then cross-multiplying gives . Taking the square root of both sides, we get as the geometric mean of and .
More generally, the geometric mean of a set of numbers is the th root of their product.
Example 1:
Find the geometric mean of and
There are two numbers. So, the geometric mean of the two numbers is the square root of their product.
Geometric mean
The geometric mean of and is .
Example 2:
Find the geometric mean of , and .
There are three numbers. So, the geometric mean of the three numbers is the cube root of their product.
Geometric mean
The geometric mean of , and is .