Analyze the effect on the graph of f(x)=lnx

when f(x)
is replaced by −1/7f(x)
.(1 point)
Responses

The graph reflects across the y-axis and vertically stretches by a factor of 7.
The graph reflects across the y -axis and vertically stretches by a factor of 7.

The graph reflects across the x-axis and vertically stretches by a factor of 7.
The graph reflects across the x -axis and vertically stretches by a factor of 7.

The graph reflects across the x-axis and vertically compresses by a factor of 1/7
.
The graph reflects across the x -axis and vertically compresses by a factor of Start Fraction 1 over 7 End Fraction .

The graph reflects across the y-axis and vertically compresses by a factor of 1/7
.
The graph reflects across the y -axis and vertically compresses by a factor of Start Fraction 1 over 7 End Fraction .

1 answer

To analyze the transformation of the graph of \( f(x) = \ln x \) when it is replaced by \( -\frac{1}{7} f(x) \), we start by examining the effect of each component in the new function.

  1. Negative Sign (-): The negative sign indicates a reflection across the x-axis. So, \( -f(x) \) means that the output values of the function are inverted.

  2. Multiplication by \( \frac{1}{7} \): This indicates a vertical compression by a factor of 1/7. When a function \( f(x) \) is multiplied by a positive constant \( k \) (less than 1), it compresses the graph vertically. In this case, since \( f(x) \) is multiplied by \(-\frac{1}{7}\), it reflects across the x-axis and compresses the output values.

Putting these two transformations together, we can conclude that replacing \( f(x) \) with \( -\frac{1}{7} f(x) \) results in:

  • A reflection across the x-axis (due to the negative sign).
  • A vertical compression by a factor of \( \frac{1}{7} \) (due to the multiplication by \( \frac{1}{7} \)).

Therefore, the correct response is:

The graph reflects across the x-axis and vertically compresses by a factor of \( \frac{1}{7} \).