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Mathematics 13 Online
OpenStudy (zab505):

Which function is the inverse of F(x) = b^x?

OpenStudy (zab505):

OpenStudy (mathmale):

I'd suggest that you actually find the inverse of the given function, and then compare your result to the four possible answer choices. If F(x) = b^x, replace "F(x)" with y. Would you do that now, please?

OpenStudy (zab505):

f^(-1) (x) = (log(x))/(log(b))

OpenStudy (zab505):

Now what?

OpenStudy (mathmale):

I haven't actually worked this problem through yet, but will do it now. I asked you to replace "F(x)" with y; the resulting equation is y = b^x. You apparently were able to do muhc more than that; your result agrees with mine. Just label it \[F ^{-1}(x)\] to match up with the original F(x).

OpenStudy (mathmale):

Does this correspond to any of the four possible answer choices?

OpenStudy (zab505):

not sure?

OpenStudy (larseighner):

I don't know the Socratic way to get to a definition, but this what you need to know: \( \displaystyle \begin{gather} \text{for } b \ge 0\text{, } b \ne 1 \text{, } \text{ and } y \gt 0 \text{, } \cr y=b^x \iff x = \log_b y \end{gather} \) And g(x) and f(x) are inverse functions if g(f(x)) = x = f(g(x))

OpenStudy (zab505):

Ah so D?

OpenStudy (mathmale):

Yes, I'd go along with that. Note that I obtained the expression\[\frac{ \ln x }{ \ln b }\]

OpenStudy (mathmale):

which is part of the "change of base formula."

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