Answer
a) $2\sqrt 2$
b) $2\sqrt 2$
c) $1$
d) $0$
Work Step by Step
(a) $(f\circ g)(4)= f(g(4))=f(2\times4)=f(8)=\sqrt 8=2\sqrt 2$
(b) $(g\circ f)(2)=g(f(2))=g(\sqrt 2)=2\times\sqrt 2=2\sqrt 2$
(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\times0)$$=g(0)=2\times0=0$
