производная 
y=sin(2*x)/(4*cos(3*x))

u=sin(2x)    v=4cos(3x)
u'=2cos2x    v'=-4*3sin3x=-12sin3x
y'=(u/v)'=1/v²[u'v-v'u]
y'=1/16cos²3x[2cos2x*4cos3x+12sin3x*sin2x]