I'm looking to integrate:

1/(2x+5)

Wolframalpha.com displays the answer as:

1/2 log(2x+5)

My problem is with the (1/2) in the answer. Wolfram claims that you substitute u=2x+5 and du=2dx, but then goes on to take the 1/2 out before substituting then integrating...

Could someone take me step by step through this?