Compare the functions f(x)=8x

and g(x)=log8x
. The graph of f(x)
contains the points (1,8)
and (−1,0.125)
. Select the answer choice that contains two points on the graph of g(x)
.(1 point)
Responses

(1,8)
and (−1,0.125)
left parenthesis 1 comma 8 right parenthesis and left parenthesis negative 1 comma 0.125 right parenthesis

(−1,−8)
and (1,−0.125)
left parenthesis negative 1 comma negative 8 right parenthesis and left parenthesis 1 comma negative 0.125 right parenthesis

(1,0.125)
and (−1,8)
left parenthesis 1 comma 0.125 right parenthesis and left parenthesis negative 1 comma 8 right parenthesis

(8,1)
and (0.125,−1)

1 answer

To analyze the functions \( f(x) = 8x \) and \( g(x) = \log_8(x) \), we first need to understand their characteristics and quickly determine points on the graph of \( g(x) \).

  1. For \( f(x) = 8x \):

    • When \( x = 1 \): \[ f(1) = 8(1) = 8 \] So the point \( (1, 8) \) is correct.
    • When \( x = -1 \): \[ f(-1) = 8(-1) = -8 \] Thus, the point \( (-1, -8) \) is actually on the graph, but the earlier provided point \( (-1, 0.125) \) appears to refer to values from \( g(x) \) instead.
  2. For \( g(x) = \log_8(x) \):

    • To find points on \( g(x) \), we can convert the values for \( f(x) \) based on the logarithmic relationship:
      • Specifically, if \( f(x) = 8x \) yields \( y \), then we want to find \( x \) such that \( g(y) = \log_8(y) \).

Now let's see the given options:

  1. \( (1, 8) \) and \( (-1, 0.125) \) - \( (-1, 0.125) \) does not match \( g(x) \)'s values.
  2. \( (-1, -8) \) and \( (1, -0.125) \) - No valid since \( y \) can't be negative for \( g(x) \).
  3. \( (1, 0.125) \) and \( (-1, 8) \) - Here, \( (1, 0.125) \) makes sense since \( g(0.125) = \log_8(0.125) \), while the second part is from \( f(x) \).
  4. \( (8, 1) \) and \( (0.125, -1) \) - The first point is valid since \( g(8) = 1 \), but \( (0.125, -1) \) is wrong in terms of \( g(x)\) since it cannot return negative values.

Based on the function \( g(x) \):

  • Calculate:
    • \( g(8) = \log_8(8) = 1 \)
    • \( g(0.125) = \log_8(0.125) = -1 \)

Thus, the better selection based on these evaluations: The correct answer would be:

(8, 1) and (0.125, -1)

This appears valid due to the nature of the logarithmic function mapping valid domains; however, care is needed since:

The final response aligns best with the fact that \( g(8) = 1 \) is correct, despite any misalignment in response structure.