The function \(y\) is defined by \(y=3x-2x^2\). Write down its derivative and show that, when \(x=5\), a small increase in \(x\) of \(p\%\) causes an increase in the magnitude of \(y\) of approximately \(\dfrac{17p}{7}\%\).

The function \(y\) is defined by \(y=3x-2x^2\). Write down its derivative and show that, when \(x=5\), a small increase in \(x\) of \(p\%\) causes an increase in the magnitude of \(y\) of approximately \(\dfrac{17p}{7}\%\).