((1-x)/(1+x))

If (1+x)(1+2x)(1+3x)((1+x)(1+2x)(1+3x))/((1-x)(1-2x)(1-3x))=K+(A)/(1-x)+(B)/(1-2x)+(C)/(1-3x) Then which of the following is correct?

Let f(x) = ((1 - x(1+ |1-x | )) /(|1-x|)) cos(1/(1-x)) for x!=1

Let f(x)=((1-x(1+|1-x|))/(|1-x|))cos((1)/(1-x)) for x!=1

Let f(x) = ((1 - x(1+ |1-x | )) /(|1-x|)) cos(1/(1-x)) for x!=1