Solve quadratic equation by factoring and using the zero product rule
When solving linear equations such as 2x - 5 = 21 we can solve for the variable directly by adding 5 and dividing by 2 to get 13. However, when we have [latex]{x}^{2}\\[/latex], or a greater power of x, we cannot just isolate the variable as we did with the linear equations. One method that we can use to solve for the varaible is known as the zero product rule
Zero Product Rule: If ab = 0 then either a = 0 or b = 0
The zero product rule tells us that if two factors are multiplied together and the answer is zero, then one of the factors must be zero. We can use this to help us solve factored polynomials as in the following example