Optimization Basics 181103
1. Let's state the problem: Optimization involves finding the maximum or minimum value of a function, often subject to certain constraints.
2. The general approach uses the derivative: To find extrema (maxima or minima), we find where the derivative of the function equals zero, i.e., solve $f'(x) = 0$.
3. Important rules:
- Critical points occur where $f'(x) = 0$ or $f'(x)$ is undefined.
- Use the second derivative test: if $f''(x) > 0$, the point is a local minimum; if $f''(x) < 0$, it is a local maximum.
4. Steps to solve an optimization problem:
- Define the function to optimize.
- Find its derivative.
- Solve $f'(x) = 0$ to find critical points.
- Use the second derivative test or analyze endpoints to determine maxima or minima.
5. Example: Suppose we want to maximize $f(x) = -2x^2 + 4x + 1$.
- Derivative: $f'(x) = -4x + 4$.
- Set derivative to zero: $-4x + 4 = 0 \Rightarrow x = 1$.
- Second derivative: $f''(x) = -4 < 0$, so $x=1$ is a maximum.
- Maximum value: $f(1) = -2(1)^2 + 4(1) + 1 = -2 + 4 + 1 = 3$.
This is the basic method for optimization problems.