121k views
2 votes
Find the domain, x-intercept, and vertical asymptote of the logarithmic function.f(x) =log(x−3)+4

Find the domain, x-intercept, and vertical asymptote of the logarithmic function.f-example-1
User Przemek K
by
6.4k points

1 Answer

4 votes

Solution:

Given the logarithmic function:


f(x)=\log(x-3)+4

Domain:

The domain of the function is the set of input values for which the function is real and defined.

From f(x) function:


f(x)=\operatorname{\log}(x-3)+4

The domain of the function is


x>3

x-intercept:

The x-intercept of the function is the value of x for which the function f(x) equates to zero.

Thus,


\begin{gathered} f(x)=\operatorname{\log}(x-3)+4 \\ where\text{ f\lparen x\rparen=0} \\ \Rightarrow\operatorname{\log}(x-3)+4=0 \\ subtract\text{ 4 from both sides of the equation} \\ \operatorname{\log}(x-3)+4-4=0-4 \\ \Rightarrow\operatorname{\log}(x-3)=-4 \\ take\text{ the antilogarithm of both sides,} \\ 10^{\operatorname{\log}(x-3)}=10^(-4) \\ \Rightarrow x-3=0.0001 \\ add\text{ 3 to both sides of the equation} \\ x-3+3=0.0001+3 \\ \Rightarrow x=3.0001 \end{gathered}

Hence, the x-intercept of the function is


(3.0001,\text{ 0\rparen}

Vertical asymptote:

The vertical asymptote of the logarithm function in the form


y=alog(x+h)+k

will have its vertical asymptote at


x=-h

Thus, the vertical asymptote of the logarithm function:


f(x)=\operatorname{\log}(x-3)+4

is


\begin{gathered} x=-(-3) \\ \\ \end{gathered}

Hence, the vertical asymptote of the f(x) function is


x=3

User Eheydenr
by
6.0k points