The acceleration \( a(x) \) is the rate of change of velocity with respect to time, given by the formula:
\[
a(x) = \frac{dv}{dt}.
\]
Using the chain rule, we express this as:
\[
a(x) = v'(x) \cdot v(x),
\]
where \( v(x) = 3x^2 - 4x \). First, we differentiate \( v(x) \):
\[
v'(x) = \frac{d}{dx}(3x^2 - 4x) = 6x - 4.
\]
Now, the acceleration is:
\[
a(x) = (6x - 4) \cdot (3x^2 - 4x).
\]