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: 68

Answer

Zeros: $7,-2$ $x$-intercepts: $7,-2$

Work Step by Step

To find the zeros of a function $f$, solve the equation $f(x)=0$ The zeros of the function are also the $x-$intercepts. Let $H(x)=0$: $$(2-x)^2+(2-x)-20=0$$ Let $u=2-x$, the original equation becomes $$u^2+u-20=0$$ By factoring $$(u+5)(u-4) = 0$$ Use the Zero-Product Property by equating each factor to zero, then solve each equation ton obtain:: \begin{align*} u +5&=0 &\text{ or }& &u-4=0\\ u &= -5 &\text{ or }& &u=4\\ \end{align*} To solve for $x$, we use $u=2-x$ $$\because u = 2-x$$ $$\therefore x = 2-u$$ For $u=-5$ $$x=2-(-5) $$ $$x= 7$$ For $u=4$ $$x=2-4$$ $$x= -2$$ $\therefore x =7,-2$
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