This week in Precalc 11 we covered the basics of factoring and we also got to touch on solving quadratic equations using factoring.
What makes something a quadratic equation:
- Quadratic equations are polynomial equations of degree 2.
- General form: ax^2+bx+c=0
- have to make one side equal to zero when factoring
- there will be up two answers when factoring them
- follows the zero product law: the zero product law states that if the product of two factors is zero, then at least one of the factors must be zero.
Example 1:
step 1: Factor – you want to first look for any common variables or numbers, if there aren’t any you can factor by your prefered method (boxing, grouping, inspection, etc) the numbers that are on the other side of the zero. (during factoring quadratic quations we do not touch the zero it just stays there, because essentially the whole point is to get the none zero side to equal zero.)
step 2 : apply the zero product law – applying the zero-product property helps us find the values of x that make each factor equal to zero, thus giving us the solutions to the quadratic equation. For example -8 x 8 = 0
A great way to check to see if you have done your work correctly, is to just plug back in the number to the original equation.
Example 2 : As we can see in this example, we didn’t have all the number on one side and zero on another, but thats okay because all we need to do is to move them to one side. The reason as to why the answers are fractions is because when applying the zero product law, we are taking the equation and isolating x.
Example 3: in this example we are dealing with fractions. After moving the constant to the left hand side, we multiply everything by 6 because 6 is the least common multiple. then we factor, group and apply the zero product law.