To solve the given expression, we need to evaluate the function \( g \) at \( 6a \) and then multiply the result by \( \frac{1}{2} \). Since the function \( g \) is not defined in the question, we will assume it is a placeholder for any function. We will write a Python function to represent \( g \) and then compute the expression.
Step 1: Define the Function \( g(x) \)
Assume the function \( g(x) \) is defined as \( g(x) = x^2 \).
Step 2: Substitute \( x = 6a \) into \( g(x) \)
Substitute \( x = 6a \) into the function \( g \):
\[ g(6a) = (6a)^2 \]
Step 3: Simplify the Expression
Simplify the expression:
\[ g(6a) = 36a^2 \]
Step 4: Multiply by \( \frac{1}{2} \)
Multiply the result by \( \frac{1}{2} \):
\[ \frac{1}{2} g(6a) = \frac{1}{2} \times 36a^2 = 18a^2 \]
Step 5: Substitute \( a = 3 \)
Substitute \( a = 3 \) into the expression:
\[ 18a^2 = 18 \times 3^2 = 18 \times 9 = 162 \]