Q: after I updated to OS X Yosemite, my macbook air become hot and its battery running out fast. can help me?

Hello nurul bahriah,

Thanks for using Apple Support Communities.

If you're experiencing issues with your Mac's battery running out and temperature increasing, then there might be a process running on the Mac that's causing both to occur.  To help troubleshoot this issue please follow the steps in the link below.

Apps can affect Mac performance, battery runtime, temperature, and fan activity - Apple Support

Take care.