A function and its reflection can be identified by the following equations: f(x)=x−2

and f′(x)=−2−x
. Determine the line of reflection. Enter the option number of your answer.

Option #1: the x-axis

Option #2: the y-axis

Option #3: y=x

Option #4: y=−x

(1 point)
The line of reflection is Option #
.

1 answer

To find the line of reflection between the function \( f(x) = x - 2 \) and its reflection \( f'(x) = -2 - x \), we need to identify what line reflects points from the first function to the second.

The equations given are:

  • \( f(x) = x - 2 \)
  • \( f'(x) = -2 - x \)

Now, let's analyze the two functions:

  1. The function \( f(x) = x - 2 \) represents a line with a slope of 1, which has a y-intercept of -2.
  2. The function \( f'(x) = -2 - x \) can be rewritten as \( f'(x) = -x - 2 \), which represents a line with a slope of -1, and also has a y-intercept of -2.

To find the line of reflection, we can check what line would reflect points from \( f \) to \( f' \). The slopes of the functions suggest that they are symmetrical with respect to the line \( y = -x \).

To verify:

  • Reflecting a point \( (a, b) \) across the line \( y = -x \) gives the point \( (-b, -a) \).
  • If we take the point on the line \( f(x) \), for example, when \( x = 0 \): \[ f(0) = 0 - 2 = -2 \] The point \( (0, -2) \) reflects to the point \( (2, 0) \).
  • If you substitute \( x = 2 \) into \( f' \): \[ f'(2) = -2 - 2 = -4 \] The point \( (2, -4) \) doesn’t match.

Instead, we can also find the midpoints of points on each function to check for reflection. Since \( f \) and \( f' \) have slopes that are negatives of each other, their reflection line should ideally bisect the angle formed by them, confirming \( y = -x \).

With these analyses considered, the correct line of reflection for the provided functions is:

Option #4: y = -x.

Therefore, the line of reflection is Option #4.