(b)
G$iven\ ,g(x) = \lbrack f{\left( 2f(x) + 2 \right)\rbrack}^{2}$
$\therefore g^{'}(x) = 2.f\left( 2f(x) + 2 \right).f^{'}\left( 2f(x) + 2 \right).2f^{'}(x)$
$= 4\ f\left( 2f(x) + 2 \right)f^{'}\left( 2f(x) + 2 \right)f^{'}(x)$
$\therefore g^{'}(0) = 4f(0)f^{'}(0)f^{'}(0) = - 4$