Dear Alejandro Jakubi,

  Thank you very much for your timely help. I am able to find the roots.

Dear Alejandro Jakubi,

 I am trying to find the root of the equation z-A=0 for the same problem. It is not working. I have used another way, first simplify(z-A) and then finding the Numerator and Denominator of that expression. For both the cases I get the error message : Error, (in fsolve/checkrange) cannot determine if this expression is true or false. I have attached the code.

Please let me know how to solve these issues. Please point me any good document for solving these issues.Coefficient_Extract_.mw

Dear Alejandro Jakubi,

Sorry for late reply because I went on vacation.

 I am able to find the coefficient of C(k) by using your method. I have compared both the results between your method and PolynomialTools:-CoefficientList , it is exactly matching. Thank you very much for your help.

Dear Experts,

 I went for Vacation. Many many thanks for your timely help, finally I am able to find out the k-th co-efficient of z^k. Now I have similar problem for fraction values inside B(z) function. I am unable to get the output of convert(B(z),FormalPowerSeries,z) function as summation and hence unable to find the k-th co-efficient using op[1,1]. I have attached the Maple file. Please help me.Quest_FormalPower_Co.mw