Is it possible to find the solutions of an equation just by looking at the numbers in this: (w-8)(w+12)?

Since (w - 8), then the solution for w equals positive 8 and since (w + 12) then solution for w = - 12?? Somewhere I learned that you can find the solutions in this way, but I am not completely sure. The original problem was about finding the perimeter of a rectangle.
Update: That is, you take the number in each parenthesis and just put the opposite sign on them and that is your solutions for the equation?
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