To find the length of the line \( x \) using the geometric mean, we can use the property of right triangles that states if a line is drawn from the vertex of the right angle to the hypotenuse, the length of that line is the geometric mean of the lengths of the two segments it creates on the hypotenuse.
In this case, the hypotenuse is divided into two segments of lengths 6 and 3.
The geometric mean \( x \) can be calculated using the formula:
\[ x = \sqrt{(6)(3)} \]
Now, calculate \( x \):
\[ x = \sqrt{18} \]
Calculating the square root:
\[ x \approx 4.2426 \]
Rounding to the nearest tenth:
\[ x \approx 4.2 \]
Thus, the length of the line \( x \) is approximately 4.2.