Solving Quadratic Equations by
Factoring
January 6, 2015
Pages 48-49
Warm-Up – pg. 48(left side)
• Factor the following expressions:
• x2 + 2x – 99
• x2 – 5x
• 7x2 + 23x + 6
Objective
solve quadratic equations and
inequalities using graphs, tables, and
algebraic methods.[8.D]
Title – pg. 49 (Right Side)
Solving Quadratic Equations by Factoring
Essential Question
• How do I use what I already know about
factoring to find the solutions to a quadratic
equation?
To Solve Quadratic Equations by
Factoring:
• Set the equation equal to 0.
• Factor the side of the equation not equal to
zero.
• Set each factor equal to 0 and solve each
equation to find your values for x.
• Check by plugging in each answer to the
original equation!
Example 1
• x2 = x + 30
Example 2
• 3x2 – 8 = 10x
Example 3
• x2 – 2x = 0
Example 4
• 8x + 24 = 2x2
Example 5
• 8x2 – 5x = 2x2 + 6x – 4
Common Mistakes
• https://learnzillion.com/lessons/745-solve-aquadratic-equation-by-factoring
• 0:41 – 2:05
Think about it… (Reflection)
• How are your answers related to the
simplified fractions you use when factoring?