To reflect a point across a vertical line, like $x = 3$, we use the concept that the reflected point should be equidistant from the line as the original point but on the opposite side.

1. The original point is $(4, -9)$.
2. The line of reflection is $x = 3$.
3. The horizontal distance from $x = 3$ to $x = 4$ is $4 - 3 = 1$.
4. Reflecting across $x = 3$, we move 1 unit to the left of the line, resulting in a new x-coordinate of $3 - 1 = 2$.

The y-coordinate remains the same because the reflection is only affecting the x-coordinate.

Thus, the coordinates of the reflected point are: $(2, -9)$

Would you like further details on this reflection process or have additional questions?

Here are 5 related questions to explore further:

1. How would you reflect a point across the line $y = c$ instead?
2. What is the process to reflect a point across the origin?
3. How do reflections differ from translations?
4. How can reflections be represented with matrix transformations?
5. How would you reflect a point across a diagonal line like $y = x$?

Tip: When reflecting over vertical or horizontal lines, only the coordinate perpendicular to the line changes.