what is the relationship between lnx and 1/x? Solution The relation between ln x and (1/x) is explained in terms of definite and indefinte integrals. Indefinite integral: Int (1/x) dx + C = lnx +C. Definite integral: {Int (1/t) dt from t = 0 to t = x} = lnx. Or in other words ln (x) is the area under the curve f(x) = ln(t) between the ordinates t= 0 to t = x, which could be calculated by evaluation of the definite integral Int (1/t)dt from t = 0 to t =x..