A basic calculator in Python
Welcome to Code Review :)
Here are some nits and tips to get you on your way.


It is much more Pythonic to define your functions outside the user flow and put the user flow inside of a main() function. The flow should look like this:

def bodmas():
    ...

def sqrt_n():
    ...

def main():
    print("""Choose from
        ...
    """)
    choose = input("enter required number \n")
    if choose == '1':
        ...
        bodmas()
        ...
    elif choose == '2':
        ...

Use an if __name__ == '__main__': guard to invoke your main() function.

if __name__ == '__main__':
    main()

Do you want to handle and catch errors?

A = int(input("Enter coefficient A: "))
...
sol1 = (-B-cmath.sqrt(D))/(2*A)


What if the user enters a non-numeric coefficient? Or what if the user enters 0? This is also applicable if the user tries to divide by zero in the bodmas() function.
Consider following a style guide like PEP8 to make your code more readable and consistent.


Happy coding!