The least common multiple (LCM) of two monomials is the smallest monomial that is a multiple of both monomials. To find the LCM of 26ab^2 and 28ac^3, we need to identify the highest power of each variable that appears in either monomial. The LCM will then be the product of these highest powers, along with any remaining unique factors. In this case, the LCM of 26ab^2 and 28ac^3 is 364a^1b^2c^3.