The function \(y\) is defined by \(y=\dfrac{\ln(4x^2-1)}{x+2}\).

(i) State the values of \(x\) for which \(y\) is not defined.

(ii) Find \(\dfrac{dy}{dx}\).

(iii) Hence find the approximate increase in \(y\) as \(x\) increases from \(2\) to \(2+h\), where \(h\) is small.