What are the asymptotes of the functions "f(x) = 4x" and "g(x) = log5x"?

for y = 4 x there is no asymptote

for log5 x
log of zero is -oo for any base
because
base^log x = x
5^what? = 0
5^-huge number = 5/huge number --->0
so log5 zero = - huge number