Hi Insaf,
I am assuming, you want to find the approximate with the Taylor series expansion of f up to the second order.
You can achieve this using "taylor" function. Here is the sample code for your reference:
syms x(theta) alpha r a
f = x(theta) + alpha * (r + x(theta))^a
taylor_expansion = taylor(f, 'Order', 2)
Refer to the following documentation for more information on "taylor" function:
