To find the shortest leg \( x \) of a triangle using the geometric mean, we can use the property of right triangles and the geometric mean. In a right triangle, the geometric mean of the lengths of the two legs is equal to the length of the altitude from the right angle to the hypotenuse.
In your case, you have two sides of lengths 3 and 5. Let's denote the lengths of the two legs as \( a = 3 \) and \( b = 5 \).
The geometric mean of the two sides is calculated using the formula:
\[ x = \sqrt{a \cdot b} \]
Substituting the given values:
\[ x = \sqrt{3 \cdot 5} = \sqrt{15} \]
Now, we can compute \( \sqrt{15} \):
\[ \sqrt{15} \approx 3.87298 \]
Rounding this to the nearest tenth gives:
\[ x \approx 3.9 \]
However, since 3.9 is not one of the provided answer options, we should double-check what you are specifically trying to solve for. The answers provided do not seem to directly connect to the geometric mean of the two numbers directly.
If we are instead looking for the area of a triangle where 3 and 5 are the legs, the relationship would differ.
Please clarify or confirm the setup or context in which you want me to find a value for \( x \) with respect to triangle relationships or if there’s a specific triangle property being looked at.