This is false...more from Business Insider:
"It's a safe bet that at some point you know someone who compulsively shuts off apps on their smartphone to save battery.
They hit the home button twice, and then swipe up on various apps they've used in the past until the carousel is cleared.
In fact, this does not save battery, and may actually use extra power when you re-open apps you've totally switched off. Apple's top software executive even confirmed this in an email to a user.
'You should force an app to close only when it's unresponsive,' Apple wrote in a support page.
You can read a more thorough debunking of this myth here." To learn about more battery myths click here.