On the Linux machines, here is the od command to display the portion of sumFirst.o containing only the sumFirst function:

od -A x -t x1 -j 52 -N 45 sumFirst.o

-A x means display addresses in x notation
-t x1 means display bytes in x notation in groups of 1 byte
-j 52 means skip the first 52 bytes
-N 45 means limit the bytes displayed (dumped) to 45 bytes.
     

The output of this command:

000034 55 89 e5 83 ec 10 c7 45 f8 00 00 00 00 c7 45 fc
000044 01 00 00 00 eb 0a 8b 45 fc 01 45 f8 83 45 fc 01
000054 8b 45 fc 3b 45 08 7e ee 8b 45 f8 c9 c3
000061
     

Machine code is not for human reading!

The od utility doesn't know anything about C programs or machine instructions; it just dumps the bytes of any file.