1. Chapter 3 3-4 factoring polynomials

4. Objectives Use the Factor Theorem to determine factors of a polynomial. Factor the sum and difference of two cubes.

5. Factor Theorem  Recall that if a number is divided by any of its factors, the remainder is 0. Likewise, if a polynomial is divided by any of its factors, the remainder is 0.  The Remainder Theorem states that if a polynomial is divided by (x – a), the remainder is the value of the function at a. So, if (x – a) is a factor of P(x), then P(a) = 0.

6. Factor theorem

7. Example#1  Determine whether the given binomial is a factor of the polynomial P ( x ).  A. ( x + 1); ( x 2 – 3 x + 1)  B. ( x + 2); (3 x 4 + 6 x 3 – 5 x – 10)

8. Example#2  Determine whether the given binomial is a factor of the polynomial P ( x ).  a. ( x + 2); (4 x 2 – 2 x + 5)

9. Student guided practice  Do problems 1-3 in your book page 177

10. Factoring  You are already familiar with methods for factoring quadratic expressions. You can factor polynomials of higher degrees using many of the same methods you learned.

11. Factoring by Grouping  Factor: x 3 – x 2 – 25 x + 25.  Factor: 2 x 3 + x 2 + 8 x + 4.

12. Factoring polynomials  Just as there is a special rule for factoring the difference of two squares, there are special rules for factoring the sum or difference of two cubes.

13. Factoring the Sum or Difference of Two Cubes  Factor the expression.  4 x 4 + 108 x  125 d 3 – 8

14. Student guided practice  Do problems 4-8 in your book page 176

15. Geometry Application  The volume of a plastic storage box is modeled by the function V ( x ) = x 3 + 6 x 2 + 3 x – 10. Identify the values of x for which V ( x ) = 0, then use the graph to factor V ( x ).

16. Geometry application  The volume of a rectangular prism is modeled by the function V ( x ) = x 3 – 8 x 2 + 19 x – 12, which is graphed below. Identify the values of x for which V ( x ) = 0, then use the graph to factor V ( x ).

17. Homework  Do odd problems from 17-32 in your book page 177

18. closure  Today we learned about polynomials  Next class we are going to learned about finding real roots in polynomials