The function y = x^2 + 2 undergoes a reflection. Which of the following could NOT represent f ' (x), the image of f after the reflection?

A. y = x^2
B. 160
C. y = -x^2
D. y = x^2 - 4x + 5

1 answer

The original function is \( y = x^2 + 2 \). If this function undergoes a reflection, we could consider two common types of reflections: reflection across the x-axis and reflection across the y-axis.

  1. Reflection across the x-axis: This would negate the output of the function, changing it to \( y = -(x^2 + 2) = -x^2 - 2 \).

  2. Reflection across the y-axis: This would negate the input of the function, changing it to \( y = (-x)^2 + 2 = x^2 + 2 \).

Now, let's examine the options provided for \( f'(x) \):

A. \( y = x^2 \): This represents a parabola that opens upwards and does not reflect the original function in the x-axis. Therefore, it is possible by shifting downwards.

B. \( 160 \): This is a constant function. A reflection would not produce a constant value like this, so this could NOT represent the image of the original function.

C. \( y = -x^2 \): This represents a downward-facing parabola, which could result from reflecting across the x-axis. This is a valid outcome for a reflection.

D. \( y = x^2 - 4x + 5 \): This can be rearranged to the vertex form and can result from transformations of the original function (\( y = x^2 + 2 \)). Hence, this could represent a valid reflection or transformation.

Given all this, the option that could NOT represent \( f(x) \) after a reflection is:

B. 160.