Question

Given that the antiderivative of f of x equals 1 divided by x is F(x) = Ln|x| + C, evaluate the integral from 1 to 2 of the 1 divided by x, dx.

Answer 1

By the fundamental theorem of calculus,

$\displaystyle \int_1^2 \frac1x \, dx = F(2) - F(1) = \ln|2| - \ln|1| = \boxed{\ln(2)}$