Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 6 - Radical Functions and Rational Exponents - 6-6 Function Operations - Practice and Problem-Solving Exercises - Page 401: 20

Answer

$\frac{g}{f}(x) = \frac{1}{2x - x^2}$ $\text{Domain: all real numbers except } 0$ and $-2$

Work Step by Step

This exercise asks us to divide one function by another. Let's write out the problem: $\frac{g}{f}(x) = g(x) \div f(x) = \frac{\frac{1}{x}}{2 - x}$ When we divide by a fraction, we multiply by its reciprocal: $\frac{g}{f}(x) = g(x) \div f(x) = (\frac{1}{x})(\frac{1}{2 - x})$ Multiply: $\frac{g}{f}(x) = g(x) \div f(x) = \frac{1}{2x - x^2}$ When we find the domain, we want to find which values of $x$ will cause the function to become undefined; in other words, we want to find any restrictions for $x$, so we set the denominator equal to $0$ and solve: $2x - x^2 = 0$ Rewrite in terms of decreasing powers: $-x^2 + 2x = 0$ Factor out any common terms: $-x(2 + x) = 0$ Set the first factor equal to $0$: $-x = 0$ Divide both sides by $-1$ to solve for $x$: $x = 0$ Set the second factor equal to $0$: $2 + x = 0$ Subtract $2$ from each side of the equation: $x = -2$ In this exercise, $x$ can be any real number except for $0$ or $-2$.
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