I need help on coding this problem in Python 2.7

The objective of this problem is to compare second-order accurate forward, backward, and centered finite-difference approximations of the first derivative of a function to the actual value of the derivative. This will be done for f(x) = e^-2x - x (a) Use calculus to determine the correct value of the derivative at x = 2. (b) To evaluate the centered finite-difference approximations, start with x = 0.5. Thus, for the first evaluation, the x values for the centered difference approximation will be x = 2 plusminus 0.5 or x = 1.5 and 2.5. Then, decrease in increments of 0.01 down to a minimum value of Delta x = 0.01. (c) Repeat part (b) for the second-order forward and backward differences