Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 1 - 1.6 - Other Types of Equations - 1.6 Exercises - Page 128: 7


Solutions: $x=0$ $x=-3$

Work Step by Step

$5x^3+30x^2+45x=0$ $5x(x^2+6x+9)=0$ $5x[x^2+2(3)x+3^2]=0$ $5x(x+3)^2=0$ $5x=0$ $x=0$ or $(x+3)^2=0$ $x+3=0$ $x=-3$ Check the solutions: $x=0$: $5(0)^3+30(0)^2+45(0)=0+0+0=0$ $x=-3$: $5(-3)^3+30(-3)^2+45(-3)=5(-27)+30(9)-135=-135+270-135=0$
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