Chapter 12 - Exponential Functions and Logarithmic Functions - 12.1 Composite Functions and Inverse Functions - 12.1 Exercise Set - Page 787: 16

$a.\quad(f\circ g)(1) = 9$ $b.\quad(g\circ f)(1) = 3$ $c.\quad (f\circ g)(x) = 10-\sqrt{x}$ $d.\quad (g\circ f)(x) = \sqrt{10-x}$

$(f\circ g)(x)=f[g(x)]=10-g(x)$ $= 10-\sqrt{x} \qquad ... \quad(c)$ $(f\circ g)(1)=10-\sqrt{1}=9 \qquad ... \quad(a)$ $(g\circ f)(x)=g[f(x)]=\sqrt{f(x)}$ $= \sqrt{10-x} \qquad ... \quad(d)$ $(g\circ f)(1)=\sqrt{10-1}=3 \qquad ... \quad(b)$