if y = log(x), then y will have a vertical asymptote when x = 0
To find the verical asymptote of a logaritmic expression log(g), you have to find the values when g = 0
For example:
If y = log(x - 3), then y will have a vertical asymptote when x - 3 = 0, it means that when x = 3, y has a vertical asymptote