The exponent on the integral expresssion gives it away.

After the logarithm is introduced, simply multiply and divide the integral side by . Leave the numerator outside the integral expression and put the denominator inside the integral expression.

is also constant and has been removed from the integral expression before division of the integral expression to the other side.

Watch out for these things. In practical applications, integrals, derivative, logarithms, and various other things sometimes are substituted with some form of linear approximation. That does not appear to have happened here, but keep your eyes out for it in your future readings.