Let M and m respectively be the maximum and the minimum values of f(x)= |1+ sin^2 x, cos^2 x, 4 sin 4 x; sin^2 x, 1+ cos^2 x, 4 sin 4 x; sin^2 x,…

Let M and m respectively be the maximum and the minimum values of $$f(x)=\left|\begin{array}{ccc} 1+\sin ^2 x & \cos ^2 x & 4 \sin 4 x \\ \sin ^2 x & 1+\cos ^2 x & 4 \sin 4 x \\ \sin ^2 x & \cos ^2 x & 1+4 \sin 4 x \end{array}\right|, x \in \mathrm{R} $$ Then $\displaystyle \mathrm{M}^4-\mathrm{m}^4$ is equal to :