Find the inverse of the function f(x) = 5IN(7-3x)

[Guest]

This one involves the natural log, I think.

Find the inverse of f(x) = 5IN(7-3x).

I need some tips.

 

[tkhunny]

Re: f(x) = 5IN(7-3x)

Find the inverse of f(x) = 5*ln(7-3x).

y = 5*ln(7-3x)

Swap.

x = 5*ln(7-3y)

Solve

x/5 = ln(7-3y)

\(\displaystyle e^{x/5} = 7-3y\)

\(\displaystyle 3y = 7 - e^{x/5}\)

\(\displaystyle y = (1/3)*[7 - e^{x/5}] = f^{-1}(x)\)

 

[stapel]

This one involves the natural log.... f(x) = 5IN(7-3x).

Note: The abbreviation for "natural log" is "ln"; that is, a lower-case ell-enn.

Eliz.

 

[Guest]

ok

Liz,

Thanks for letting me know about In not IN.

tkhunny,

Thanks for your help.

Does it mater if I write e^x/5 - 7 or does it have to be 7 - e^x/5?

 

[skeeter]

Re: ok

Does it mater if I write e^x/5 - 7 or does it have to be 7 - e^x/5?

does a - b = b - a if a and b are not equal to each other?

 

[stapel]

Re: ok

Thanks for letting me know about In not IN.

It's ell-enn, not eye-enn.

Eliz.

 

[tkhunny]

Re: ok

Does it mater if I write e^x/5 - 7 or does it have to be 7 - e^x/5?

It matters if it is e^x/5 of e^(x/5).