Step 1: The product of the zeroes of a quadratic polynomial \( ax^2 + bx + c \) is:
\[
\frac{c}{a}.
\]
Step 2: Given the polynomial:
\[
x^2 - 9x + a = 0.
\]
Here, the coefficient of \( x^2 \) is 1, so:
\[
\text{Product of roots} = \frac{a}{1} = a.
\]
Step 3: Setting the equation:
\[
a = 8.
\]