I'm not sure what the issue is, but I've calculated this several times and have been unable to produce the correct answer. I have followed the procedures.
I went to calculate the second Derivative using the equation
d/dt(dy/dx)/(dx/dt)1 Answer
$\begingroup$As you did, the first derivative is found by
$$y'(t)=\frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}},$$
where the "$'$" is derivative with respect to x.
Same thing for the second derivative:
$$y''(t)=\frac{dy'}{dx} = \frac{\frac{dy'}{dt}}{\frac{dx}{dt}}.$$
I get
$\endgroup$ 4$$\frac{2t}{(t+1)^3}$$
