I'm trying to prove . I'm driving myself crazy trying to figure out what N should be.
so Okay to drop the abs value,
But the left side is undefined at , and worse...it could be negative or positive. So I don't think I can proceed, right? I don't think I need to consider cases, so I think I've already done something wrong. I've tried switching the terms in the distance formula, but I end up with a similar problem (left side could be positive or negative, so I can't square it without losing the inequality).