Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 3 - Linear and Quadratic Functions - 3.5 Inequalities Involving Quadratic Functions - 3.5 Assess Your Understanding - Page 160: 22

Answer

all the real numbers

Work Step by Step

$2(2x^2-3x)>-9$, hence $4x^2-6x+9\gt 0.$ If I complete the square and divide by $6.75$, then $\frac{16}{27}\cdot(x-0.75)^2>-1$. The square of all real numbers is non-negative, hence the square of all real numbers multiplied by a positive constant is non-negative, hence the solution set is all the real numbers. (also, see the graph of $\frac{16}{27}\cdot(x-0.75)^2$
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