It seems like part of your question is missing after "f(x)," but I can help based on the provided information.

If you have $f(x) = -2x - 9$, and you're solving for $x$, it depends on what value you have for $f(x)$. For example, if you're given a specific value for $f(x)$, say $f(x) = 0$, you can solve the equation for $x$.

For instance, if: $f(x) = 0 \quad \text{then} \quad -2x - 9 = 0$

1. Add 9 to both sides: $-2x = 9$

2. Divide by -2: $x = \frac{9}{-2} = -4.5$

Would you like to clarify the missing part of your question, or is this the solution you were looking for?

---

Relative questions:

1. What if $f(x) = 1$? How would you solve for $x$?
2. How would you graph $f(x) = -2x - 9$?
3. Can you find the x-intercept and y-intercept of this function?
4. How does changing the slope of the function affect its graph?
5. What is the domain and range of this linear function?

Tip: Always isolate the variable step-by-step when solving an equation to avoid mistakes.