4 (i) Solve the equation $2 \ln ( 2 x ) - \ln ( x + 3 ) = 4 \ln 2$.\\

(ii) Hence solve the equation

$$2 \ln \left( 2 ^ { u + 1 } \right) - \ln \left( 2 ^ { u } + 3 \right) = 4 \ln 2$$

giving the value of $u$ correct to 4 significant figures.\\

\hfill \mbox{\textit{CAIE P2 2018 Q4}}