You dont need to kill those tasks. Task killers are not needed with android. Unlike Windows, Android will fill its cache full of programs to fully take advantage of the memory. Those programs are not running, just cached for when you want to open them. By killing those apps, you mess up the way android works, and android will just put those back into cache, therefore using more battery then it would if you just leave them alone.

 

A lot of those tasks are meant to run continuously in the background. If you press Alt+Ctrl+Delete on your PC and open up task manager, you will see a long list of task. Trying to shut down all of them will result in a crash.

Do a bit of trial of error and see which tasks pop up again after you have killed it. Those are the ones you do not want to kill.