How do i determine if the equation is always, never, or sometimes true

Always true:holds true no matter what and you cannot think of a counterexample or a theorem proves it like anything times 2 is even

sometimes true; holds true under some circumstances like anything times 3 is even

Never truer theorem disproves it or there are many counterexamples: negative times negative is negative

If there is an exception or counterexample whatsoever, then it is sometimes if there is no counterexample, then it is always true.