Derivatives Negative Exponents
1. **State the problem:** Find the first and second derivatives of the function $$w = 3z^{-2} - \frac{1}{z}$$.
2. **Recall the power rule for derivatives:**
- If $$f(z) = z^n$$, then $$f'(z) = nz^{n-1}$$.
- For negative exponents, the rule applies the same way.
3. **Rewrite the function for clarity:**
$$w = 3z^{-2} - z^{-1}$$
4. **Find the first derivative $$w'$$:**
$$w' = \frac{d}{dz}(3z^{-2}) - \frac{d}{dz}(z^{-1})$$
Using the power rule:
$$\frac{d}{dz}(3z^{-2}) = 3 \times (-2) z^{-3} = -6z^{-3}$$
$$\frac{d}{dz}(z^{-1}) = -1 \times z^{-2} = -z^{-2}$$
So,
$$w' = -6z^{-3} - (-z^{-2}) = -6z^{-3} + z^{-2}$$
5. **Find the second derivative $$w''$$:**
$$w'' = \frac{d}{dz}(-6z^{-3} + z^{-2}) = \frac{d}{dz}(-6z^{-3}) + \frac{d}{dz}(z^{-2})$$
Using the power rule again:
$$\frac{d}{dz}(-6z^{-3}) = -6 \times (-3) z^{-4} = 18z^{-4}$$
$$\frac{d}{dz}(z^{-2}) = -2 z^{-3}$$
So,
$$w'' = 18z^{-4} - 2z^{-3}$$
6. **Final answers:**
$$w' = -6z^{-3} + z^{-2}$$
$$w'' = 18z^{-4} - 2z^{-3}$$
These derivatives tell us how the function changes and how the rate of change itself changes with respect to $$z$$.