Factoring undoes multiplying. Given the tiles for x² + 5x + 6, slide them into a rectangle and read its sides, (x + 2)(x + 3). Pull out a common factor first, find two numbers that multiply to c and add to b, split the middle term when a is not 1, and recognize a difference of squares or a perfect square. A factored form shows the zeros of a polynomial, the inputs that make it zero, and the zeros give a rough graph.