To find the second derivative of the function \( y = \frac{1}{x^3} \), we first need to find the first derivative using the power rule. Once we have the first derivative, we apply the power rule again to find the second derivative.
Step 1: Find the First Derivative
To find the first derivative of \( y = \frac{1}{x^3} \), we apply the power rule. The power rule states that if \( y = x^n \), then \( \frac{dy}{dx} = nx^{n-1} \).
For \( y = x^{-3} \), the first derivative is:
\[
\frac{dy}{dx} = -3x^{-4} = -\frac{3}{x^4}
\]
Step 2: Find the Second Derivative
Next, we find the second derivative by differentiating the first derivative. Again, we use the power rule.
For \( \frac{dy}{dx} = -3x^{-4} \), the second derivative is:
\[
\frac{d^2y}{dx^2} = 12x^{-5} = \frac{12}{x^5}
\]
Final Answer
The second derivative of \( y = \frac{1}{x^3} \) is:
\[
\boxed{\frac{d^2y}{dx^2} = \frac{12}{x^5}}
\]