Answer
a) $2\sqrt 2$; b) $2\sqrt 2$; c) 1; d) 0.
Work Step by Step
We are given the functions:
$f(x)=\sqrt x$
$g(x)=2x$
a) $(f\circ g)(4)=f(g(4))=f\left(2(4)\right)=f(8)=\sqrt 8=2\sqrt 2$
b) $(g\circ f)(2)=g(f(2))=g(\sqrt 2)=2\sqrt 2$
c) $(f\circ f)(1)=f(f(1))=f(\sqrt 1)=f(1)=\sqrt 1=1$
d) $(g\circ g)(0)=g(g(0))=g(2(0))=g(0)=2(0)=0$
