Question

If (2, 200) lies on the line f(x)=20^x
, then what reflection point lies on the line g (x)=log20 x
?(1 point)
(
,
)

1 answer

The line \( f(x) = 20^x \) is an exponential function, and the point \( (2, 200) \) suggests that \( f(2) = 20^2 = 400 \). However, the point given is incorrect because \( 20^2 = 400 \) and not \( 200 \). Therefore, it seems there might be a misunderstanding.

Instead, if we start with the point \( (2, 400) \) that lies on \( f(x) \), we can find the reflection point on the line \( g(x) = \log_{20}(x) \).

To find the reflection, note that \( g(x) \) is the inverse function of \( f(x) \), where: \[ y = f(x) \implies x = g(y) \]

The reflection of a point \( (a, b) \) across the line \( y = x \) is given by \( (b, a) \).

First, let's verify:

  • If \( f(2) = 20^2 = 400 \), then the point corresponding to \( g(x) \) would be: \[ g(400) = \log_{20}(400) \]

Using the change of base formula, we can compute \( \log_{20}(400) \): \[ \log_{20}(400) = \frac{\log_{10}(400)}{\log_{10}(20)} \]

Since we can simplify \( 400 = 20^2 \cdot 1 = 20^2 \cdot 20^0 \): \[ 400 = 20^2 \implies \log_{20}(400) = 2 \]

Thus, the reflection point of \( (2, 400) \) across the line \( y = x \) would be: \[ (400, 2) \]

Therefore, the reflection point that lies on \( g(x) = \log_{20}(x) \) is:

\[ \boxed{(400, 2)} \]