Stitz-Zeager_College_Algebra_e-book

5 q x 5x2 6x 4 33 real zeros of polynomials 33 207

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Unformatted text preview: he Factor Theorem and The Remainder Theorem 3.2 197 The Factor Theorem and The Remainder Theorem Suppose we wish to find the zeros of f (x) = x3 + 4x2 − 5x − 14. Setting f (x) = 0 results in the polynomial equation x3 + 4x2 − 5x − 14 = 0. Despite all of the factoring techniques we learned1 in Intermediate Algebra, this equation foils2 us at every turn. If we graph f using the graphing calculator, we get The graph suggests that x = 2 is a zero, and we can verify f (2) = 0. The other two zeros seem to be less friendly, and, even though we could use the ‘Zero’ command to find decimal approximations for these, we seek a method to find the remaining zeros exactly. Based on our experience, if x = 2 is a zero, it seems that there should be a factor of (x − 2) lurking around in the factorization of f (x). In other words, it seems reasonable to expect that x3 + 4x2 − 5x − 14 = (x − 2) q (x), where q (x) is some other polynomial. How could we find such a q (x), if it even...
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This note was uploaded on 05/03/2013 for the course MATH Algebra taught by Professor Wong during the Fall '13 term at Chicago Academy High School.

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