To find \( x \) using the geometric mean of two numbers, we follow the formula:
\[ x = \sqrt{a \cdot b} \]
In this case, you've provided the numbers 5 and 3. Therefore, we can plug them into the formula:
\[ x = \sqrt{5 \cdot 3} \]
Calculating the product:
\[ 5 \cdot 3 = 15 \]
Now, we take the square root:
\[ x = \sqrt{15} \approx 3.872983346207417 \]
Rounding to the nearest tenth, we get:
\[ x \approx 3.9 \]
Thus, the value of \( x \) is approximately \( 3.9 \).