how do you close apps on the ipad now

on iPads that still have a home button it's a double-click on the home button to get the same switcher. and you can push up two or three cards at once with separate fingers. but you don't need to close them for battery, only when one is frozen.

swipe up from the bottom edge but stop halfway and hold for a second, the app switcher opens. then flick the app's card up to close it.