(1 + arctanx ) ^1/2 problem with algebra

[Riazy]

hello, If you look at the scanned paper with the red underline,, i am basically wondering why the the book author has put it inside 1/2 u

[attachment=0:1vv0ivnz]IMG_0005.jpg[/attachment:1vv0ivnz]

 

[tkhunny]

Picking the first two terms of the zrctan expansion serves as an approximation and is used as a substitution in the first expansion. What are you not seeing? It's algebra one.