is equal to \(0\) for all values of \(x\). What deduction can be made from this result?

*[By ‘the differential coefficient’, the question means ‘the derivative’.]*

Verify that the differential coefficient with respect to \(x\) of
\[\begin{equation*}
\sin^4 x + 2 \cos^2 x - \cos^4 x
\end{equation*}\]

is equal to \(0\) for all values of \(x\). What deduction can be made from this result?

*[By ‘the differential coefficient’, the question means ‘the derivative’.]*