Answer is: option2
\( -\frac{1}{2e} \)Solution:
Differentiate \( f(x) \) using the product rule.
\[ f(x) = x^2 \ln x \]
Let \( u = x^2 \) and \( v = \ln x \). Then,
\[ f'(x) = \frac{d}{dx} (x^2 \ln x) \]
Using the product rule:
\[ f'(x) = x^2 \cdot \frac{1}{x} + 2x \ln x \]
\[ = x + 2x \ln x \]
\[ = x(1 + 2 \ln x) \]
Set \( f'(x) = 0 \):
\[ x(1 + 2 \ln x) = 0 \]
Since \( x \neq 0 \), we solve:
\[ 1 + 2 \ln x = 0 \]
\[ 2 \ln x = -1 \]
\[ \ln x = -\frac{1}{2} \]
\[ x = e^{-1/2} = \frac{1}{\sqrt{e}} \]
Now, differentiate \( f'(x) = x(1 + 2 \ln x) \):
\[ f''(x) = 1 + 2 \ln x + 2 \]
\[ = 3 + 2 \ln x \]
Substituting \( x = \frac{1}{\sqrt{e}} \):
\[ f''\left( \frac{1}{\sqrt{e}} \right) = 3 + 2 \left( -\frac{1}{2} \right) \]
\[ = 3 - 1 = 2 > 0 \]
Since \( f''(x) > 0 \), \( x = \frac{1}{\sqrt{e}} \) is a local minimum.
Now, evaluate \( f(x) \) at the critical point:
\[ f\left( \frac{1}{\sqrt{e}} \right) = \left( \frac{1}{\sqrt{e}} \right)^2 \ln \left( \frac{1}{\sqrt{e}} \right) \]
\[ = \frac{1}{e} \times \left( -\frac{1}{2} \right) \]
\[ = -\frac{1}{2e} \]
Final Answer: \[ = -\frac{1}{2e} \]