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: 43

Answer

The rational zeros are $x = -1$ or $x = 5$ or $x = 2$ or $x = -\frac{1}{3}$. The polynomial in factored form is $(x - 5) (x - 2) (x + 1)^2 (3 x + 1)$.

Work Step by Step

Alternate form: $3x^5-14x^4-14x^3+36x^2+43x+10 = (x + 1)^2 (3 x^3 - 20 x^2 + 23 x + 10)$ Solve for x over the real numbers: $(x + 1)^2 (3 x^3 - 20 x^2 + 23 x + 10) = 0$ Split into two equations: $(x + 1)^2 = 0$ or $3 x^3 - 20 x^2 + 23 x + 10 = 0$ Take the square root of both sides: $x + 1 = 0$ or $3 x^3 - 20 x^2 + 23 x + 10 = 0$ Subtract 1 from both sides: $x = -1$ or $3 x^3 - 20 x^2 + 23 x + 10 = 0$ The left hand side factors into a product with three terms: $x = -1$ or $(x - 5) (x - 2) (3 x + 1) = 0$ Split into three equations: $x = -1$ or $x - 5 = 0$ or $x - 2 = 0$ or $3 x + 1 = 0$ Add 5 to both sides: $x = -1$ or $x = 5$ or $x - 2 = 0$ or $3 x + 1 = 0$ Add 2 to both sides: $x = -1$ or $x = 5$ or $x = 2$ or $3 x + 1 = 0$ Subtract 1 from both sides: $x = -1$ or $x = 5$ or $x = 2$ or $3 x = -1$ Answer: The rational zeros are $x = -1$ or $x = 5$ or $x = 2$ or $x = -\frac{1}{3}$. The polynomial in factored form is $(x - 5) (x - 2) (x + 1)^2 (3 x + 1)$.
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