Max At 12
1. The problem asks for a function that has a maximum at $x=12$ and includes an exponential component.
2. A common way to create a function with a maximum at a specific point is to use a quadratic term that opens downward, such as $-(x - h)^2$, where $h$ is the $x$-coordinate of the maximum.
3. To include an exponential function, we can multiply or add an exponential term like $e^x$ or $e^{-x}$.
4. One simple function that satisfies these conditions is:
$$f(x) = - (x - 12)^2 + e^x$$
Here, the quadratic term $-(x - 12)^2$ has its maximum at $x=12$, and the exponential term $e^x$ is included.
5. To verify the maximum at $x=12$, consider the derivative:
$$f'(x) = -2(x - 12) + e^x$$
6. At $x=12$:
$$f'(12) = -2(12 - 12) + e^{12} = 0 + e^{12} > 0$$
Since the derivative is positive, $x=12$ is not a maximum for this function as is.
7. To ensure a maximum at $x=12$, we can adjust the function to:
$$f(x) = -e^{-(x - 12)^2}$$
This function has a maximum at $x=12$ because the exponent is zero there, and the negative sign ensures a peak.
8. The derivative is:
$$f'(x) = -e^{-(x - 12)^2} \cdot (-2(x - 12)) = 2(x - 12)e^{-(x - 12)^2}$$
9. At $x=12$, $f'(12) = 0$, and the second derivative is negative, confirming a maximum.
Final answer:
$$f(x) = -e^{-(x - 12)^2}$$