[quote=alexandrabel90;505619]given that the function f(x) = l log x l where the domain is (0, infinity) and the range is real numbers. may i know why is the function not surjective?

if y has an inverse (0 to infinity)

surjective = the range is equal to the codomain

simply because y can only take positive values, so there are some elements in range(R) which are not covered