It is given that \(y=\frac{\ln(2x^2+1)}{x+2}\).

(a) Find \(\frac{\mathrm dy}{\mathrm dx}\).

(b) Given that \(x\) increases from \(2\) to \(2+h\), where \(h\) is small, find the approximate change in \(y\).

(c) Given that \(y\) is decreasing by \(0.4\) units per second, find the corresponding rate of change in \(x\) when \(x=2\).