It looks like an alternating series, so It’s likely from a physics class involving electrostatic or maybe control systems. It also could be from a later calculus class where you’re first introduced to alternating series like Taylor or Leibniz.

What issues? I have used for… I don’t even know. Feels like since my first smart phone. Never had issues.

You can tap the 3 dots next to the share button and say you’re not interested in seeing this type of stuff.

I really just want a good r/all functionality.

You don’t need the /s we all know you’re being sarcastic.