Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 2 - Linear and Quadratic Functions - Section 2.3 Quadratic Functions and Their Zeros - 2.3 Assess Your Understanding - Page 146: 30

Answer

Zeros: $\dfrac{5 \sqrt{3}}{3}+\dfrac{2}{3}$ $x$-intercepts: $ -\dfrac{5 \sqrt{3}}{3}+\dfrac{2}{3}$

Work Step by Step

To find the zeros of a function $g$, solve the equation $g(x)=0$ The zeros of the function are also the $x-$intercepts. Let $g(x)=0$: $$(3x-2)^2-75=0$$ Using the Square Root Method $$(3x-2)^2=75$$ $$ (3x-2) = \pm \sqrt{75}$$ $\sqrt{75} =\sqrt{25 \times 3} = \sqrt{25} \sqrt{3} = 5 \sqrt{3}$ $$(3x-2) = \pm 5 \sqrt{3}$$ $\therefore 3x-2 = 5\sqrt{3} \text{ or } 3x-2 = -5\sqrt{3} $ $3x-2 = 5\sqrt{3} \to 3x = 5 \sqrt{3}+2 \to x = \dfrac{5 \sqrt{3}}{3}+\dfrac{2}{3}$ $3x-2 = -5\sqrt{3} \to 3x =-5 \sqrt{2}+2 \to x = -\dfrac{5 \sqrt{3}}{3}+\dfrac{2}{3}$
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