College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 3 - Summary, Review, and Test - Cumulative Review Exercises (Chapters 1-3) - Page 440: 19

Answer

$$f(g(x)) = 32x^{2} - 20x + 2$$

Work Step by Step

The exercise is asking for a compound function of $f(x)$ and $g(x)$ which can also be expressed as $f(g(x))$. This means that we must substitute the entire function $g(x)$ into $f(x)$ as follows: $$f(g(x)) = 2(4x - 1)^{2} - (4x - 1) - 1$$ which we only need to simplify. Using the "Square of a Binomial Difference" method (see page 57 for reference), we can expand $(4x - 1)^{2}$ into $(4^{2})x^{2} - 2(4)(1)x + (1) = 16x^{2} - 8x +1$ and $$f(g(x) = 2(16x^{2} - 8x + 1) - 4x + 1 - 1$$ $$f(g(x)) = 32x^{2} - 16x + 2 - 4x$$ $$f(g(x)) = 32x^{2} - 20x + 2$$
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