title: Trying to find derivative of function using python
body: <p>I am trying to find the derivative of this function:</p>
  <p>y = 100e^-0.0482t</p>
  <p>This is the code I have:</p>
  <pre><code>import math
  from sympy import *
  import numpy as np
  x = Symbol('x')
  y = (math.exp(-.0482 * x) * 100)
  yprime = y.diff(x)
  yprimerep = y.diff(5)
  yprime
  print(yprime)
  </code></pre>
  <p>I am getting an error of:
  TypeError: can't convert expression to float</p>
  <p>Ive looked through various meanings of that error and I dont get it. any idea what Im doing wrong?</p>