Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 9 - Section 9.1 - The Algebra of Functions; Composite Functions - Exercise Set - Page 541: 52

Answer

$(f o g)(x)$ is the same as $f(g(x))$. However, $(f * g)(x)$ is the same as $f(x)*g(x)$.

Work Step by Step

Let $f(x)=x^2+2$, and let $g(x)=x-3$. $(f o g)(x) = f(g(x))$ $f(g(x)) = f(x-3)$ $f(x-3) = (x-3)^2+2$ $f(x-3) = (x-3)(x-3) +2$ $f(x-3) = x*x +x*-3 + x*-3 + (-3)(-3) +2$ $f(x-3) = x^2-3x-3x+9+2$ $f(x-3) = x^2-6x+11$ $(f * g)(x) = (x^2+2)(x-3)$ $(f * g)(x) = x^2*x+x^2*-3+2*x+2*-3$ $(f * g)(x) = x^3-3x^2+2x-6$ $x^2-6x+11$ is not the same as $x^3-3x^2+2x-6$, so the two functions are different.
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