Added exercise 5

ex_05.py

@@ -0,0 +1,17 @@
+#!/usr/bin/python3
+
+from math import sqrt as rsqrt
+from cmath import sqrt as csqrt
+
+print("I am going to compute the square root of 8")
+sqrt = rsqrt(8)
+print("The result is", sqrt)
+
+
+print("I am going to compute the square root of -4")
+sqrt = csqrt(-4)
+print("The result is", sqrt)
+
+# Note that ``callable(obj)`` returns whether ``obj`` is a 
+# callable, i.e. is a function or method or has a ``__call__`
+# method.