Solving Quadratic Equations by Factoring

January 6, 2015Pages 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-a-quadratic-equation-by-factoring

• 0:41 – 2:05

Think about it… (Reflection)

• How are your answers related to the simplified fractions you use when factoring?