Find the domain of f and f −1 and its domain. f(x) = ln(ex − 3). (a) Find the domain of f. (Enter your answer using interval notation.) (−2,[infinity]) (b) Find f −1. f −1(x) = x+ln(3)

Respuesta :

Answer:

a.Domain of f=(1.099,[tex]\infty)[/tex]

b.[tex]f^{-1}(x)=ln(e^x+3)[/tex]

Step-by-step explanation:

Let [tex]y=f(x)=ln(e^x-3)[/tex]

We know that domain of ln x is greater than zero

[tex]e^x-3>0[/tex]

Adding 3 on both sides of inequality

[tex]e^x-3+3>0+3[/tex]

[tex]e^x>3[/tex]

Taking on both sides of inequality

[tex]lne^x>ln 3[/tex]

[tex]x>ln 3[/tex]=1.099

By using [tex]lne^x=x[/tex]

Domain of f=(1.099,[tex]\infty)[/tex]

Let [tex]y=f^{-1}(x)=ln(e^x-3)[/tex]

[tex]e^y=e^x-3[/tex]

By using property [tex]lnx=y\implies x=e^y[/tex]

[tex]e^x=e^y+3[/tex]

Taking ln on both sides of equality '

[tex]lne^x=ln(e^y+3)[/tex]

[tex]x=ln(e^y+3)[/tex]

Replace x by y and y by x

[tex]y=ln(e^x+3)[/tex]

Substitute y=[tex]f^{-1}(x)[/tex]

[tex]f^{-1}(x)=ln(e^x+3)[/tex]