Question 1208214
<pre>
{{{dy/dt}}}{{{""=""}}}{{{expr((dy)/(dx))/expr((dt)/(dx))}}}{{{""=""}}}{{{sec^""(x)/(tan^""(x)-3)}}}

{{{d^2y/dt^2}}}{{{""=""}}}{{{

(  

(tan^""(x)-3)*sec^""(x)tan^""(x)*expr(dx/dt) -sec^""(x)(sec^2(x)*expr(dx/dt))  

)

/(tan^2(x)-3)^2}}}


Substitute x = 0

sec(0) = 1, tan(0) = 0

{{{dx/dt}}}{{{""=""}}}{{{tan(x)-3}}}, substitute x=0, get -3,

So {{{dt/dx}}}{{{""=""}}}{{{-1/3}}} when x=0

{{{((0-3)*1*0*(-1/3) -1(1)*(-1/3))/(0-3)^2}}}{{{""=""}}}{{{1/27}}}

Edwin</pre>