Question 929700
The vertical asymptote occurs when the argument goes to zero since the log function is not defined there.
{{{x-4=0}}}
{{{x=4}}}
.
.
{{{drawing(300,300,-2,8,-5,5,green(line(4,-10,4,10)),grid(1),graph(300,300,-2,8,-5,5,ln(x-4)))}}}