Hi there!
Recall the following relationship:
[tex]E = -\frac{dV}{dx}[/tex]
E = Electric field strength (V/m)
V = Potential Difference (V)
Take the derivative of the given electric potential equation using the power rule:
[tex]\frac{d}{dx}x^n = nx^{n-1}[/tex]
[tex]-\frac{dV}{dx} = -(3 \cdot 3 \cdot x^2) = -9x^2[/tex]
Evaluate at x = 2:
[tex]E(2) = -9(2^2) = \boxed{-36 \frac{V}{m}}[/tex]
**The magnitude of the field strength would simply be 36 V/m.
