Solving Quadratic Equations by Factoring

If A cdot B = 0, then A = 0 or B = 0 (or both). This is the foundation for solving quadratics by factoring: 1. Get everything on one side (set equation = 0) 2. Factor the quadratic 3. Set each factor = 0 4. Solve each resulting equation The solutions are also called roots, zeros, or x-intercepts of the corresponding function.

The method works for any factorable quadratic.

Example: Solve x^2 - 5x + 6 = 0

Solving by factoring is the fastest method on the SAT when the quadratic factors nicely. If you can't find the factors within 30 seconds, switch to the quadratic formula (next lesson). Also, the SAT sometimes gives you the factored form directly: "If (x - 3)(x + 7) = 0, what is a possible value of x?" — just read off the answers: x = 3 or x = -7.