I'm trying to write up dedicated answers to frequently asked questions as a comment to just link to, rather than typing it up every single time. What are some common questions that I'm missing?

I currently have these ones:

• Can I learn ___ in ___ days/weeks/months?
• I want to learn math from the basics to calculus/college math/etc.
• Is sqrt(4) just 2 or both 2 and -2?

I know I'm missing some. What are they? Also, are there any edits I should make?

I don't mean for this to be rude to anyone that asks these questions. I just typically avoid answering these questions when I've already answered them a bunch, so I wanted to at least make something to link to instead to provide them with help still. I also know the answers these posts get can sometimes be curt and brief, so I wanted to type up a detailed response for each one to provide a better answer.