P. 167, lines -4,-3 and -2

The derivatives should be:

$\frac{df}{dt}(t) = -\frac{2t}{(1+t^2)^2}$

$\frac{d^2f}{dt^2}(t) = \frac{6 t^2}{(1+t^2)^3} - \frac{2}{(1+t^2)^3}$

$\frac{d^3 f}{d t^3}(t) = -\frac{24 t^3}{(1+t^2)^4} +\frac{24 t}{(1+t^2)^4}$

Return to errata.