ValueError: math domain error

Your code is doing a log of a number that is less than or equal to zero. That's mathematically undefined, so Python's log function raises an exception. Here's an example:

>>> from math import log
>>> log(-1)
Traceback (most recent call last):
  File "<pyshell#59>", line 1, in <module>
    log(-1)
ValueError: math domain error

Without knowing what your newtonRaphson2 function does, I'm not sure I can guess where the invalid x[2] value is coming from, but hopefully this will lead you on the right track.

you are getting math domain error for either one of the reason : either you are trying to use a negative number inside log function or a zero value.

We face this problem when we use log() or sqrt() from math library. In this problem “math domain error”, we are using a negative number like (-1 or another) or a zero number where we should not be use.

You may also use math.log1p.

According to the official documentation :

math.log1p(x)

Return the natural logarithm of 1+x (base e). The result is calculated in a way which is accurate for x near zero.

You may convert back to the original value using math.expm1 which returns e raised to the power x, minus 1.