Reflection: Connection to Prior Knowledge Factoring Cubic Equations - Section 3: Making Use of Structure


As we begin factoring cubic equations, it's important to build on the students prior knowledge.  From Algebra 1, I find that many of my students are familiar with (and like to use) a "box" or "array" method.

At several points during this class, I'll take some time to explain in detail how this method can be applied to cubic functions.  The most important point is that the array must now change from a 2 x 2 box to to a 2 x 3 box.  This is due to the fact that a cubic must be divisible into one linear and one quadratic factor.  The linear factor may have up to two terms, while the quadratic may have up to three terms.

You can see one example of this method worked out on my whiteboard here and another here.

  Connection to Prior Knowledge: Methods of Factoring
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Factoring Cubic Equations

Unit 3: Cubic Functions
Lesson 4 of 13

Objective: SWBAT factor a sum or difference of two cubes. SWBAT use the distributive law to multiply a binomial by a trinomial.

Big Idea: The factored form is just as useful for solving and graphing cubic polynomials as it was for quadratics!

  Print Lesson
Math, polynomial functions, factoring polynomial expressions, cubic equations, Algebra 2, master teacher project, cubic functions, Algebra 2, function
  45 minutes
cubic polynomial
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