How to get the modulus of following complex number

I want to get the modulus of following

(1+(x+I*y)/2+(x+I*y)^2/12)/(1-(x+I*y)/2+(x+I*y)^2/12)


I use

Abs[(1+(x+I*y)/2+(x+I*y)^2/12)/(1-(x+I*y)/2+(x+I*y)^2/12)]


But I always get

                                    2
x + I y   (x + I y)
1 + ------- + ----------
2          12
Out[52]= Abs[-------------------------]
2
-x - I y   (x + I y)
1 + -------- + ----------
2           12


Can someone help me?

expr = (1 + (x + I*y)/2 + (x + I*y)^2/12)/(1 - (x + I*y)/

• Can you explain more about ComplexExand@ Abs @expr? I am new user of Mathematica.
• @Ben, the help reference.wolfram.com/language/ref/ComplexExpand.html really explains it well. Basically, if you type Abs[x + I y], then M can't do Sqrt[(x^2+y^2)] since x and y themselves can be complex numbers, each with real and imaginary parts. If that was the case, then x^2 will contains a complex value in it. So someone came up with a function to tell M to assume all symbols are real. Commented Apr 9, 2015 at 3:14