College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 3, Polynomial and Rational Functions - Section 3.4 - Real Zeros of Polynomials - 3.4 Exercises - Page 320: 42

Answer

The real zeros are $x = 2$ or $x = 3$ or $x = -1$ or $x = -2$. The polynomial in factored form is $(x - 3) (x - 2)^2 (x + 1) (x + 2)$.

Work Step by Step

Alternate form: $x^5 - 4 x^4 - 3 x^3 + 22 x^2 - 4 x - 24 = (x - 2)^2 (x^3 - 7 x - 6)$ Solve for x over the real numbers: $(x - 2)^2 (x^3 - 7 x - 6) = 0$ Split into two equations: $(x - 2)^2 = 0$ or $x^3 - 7 x - 6 = 0$ Take the square root of both sides: $x - 2 = 0$ or $x^3 - 7 x - 6 = 0$ Add 2 to both sides: $x = 2$ or $x^3 - 7 x - 6 = 0$ The left hand side factors into a product with three terms: $x = 2$ or $(x - 3) (x + 1) (x + 2) = 0$ Split into three equations: $x = 2$ or $x - 3 = 0$ or $x + 1 = 0$ or $x + 2 = 0$ Add 3 to both sides: $x = 2$ or $x = 3$ or $x + 1 = 0$ or $x + 2 = 0$ Subtract 1 from both sides: $x = 2$ or $x = 3$ or $x = -1$ or $x + 2 = 0$ Answer: The real zeros are $x = 2$ or $x = 3$ or $x = -1$ or $x = -2$. The polynomial in factored form is $(x - 3) (x - 2)^2 (x + 1) (x + 2)$.
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