Need help with this questions , Solving without function or pow from math.h

2-[30p]Harlan A. Brothers and John A. Knox discovered that as the value of x gets larger, the value of the expression (2x12x+1)x gets closer and closer to e . Write a program that evaluates this expression for x=1,2,3, and so on until the absolute difference between the expression's value and the real value of "e" is less than 0.000001. Display the value of x that causes your loop to exit along with both the final approximation of e and the real value of "e". Show 6 decimal places.(Real e=2.718281) [Do not use math.h library. For example, If you need to calculate power of number, write your own function!]