math
posted by ani .
1)d/dx of cos4x/3x^2(inculding quentient&chain rule)
2)sin^2x/1+cosx(same method)

#1
y = cos 4x/(3x^2)
dy/dx = ( (3x^2)(4sin 4x)  cos 4x (2x) )/(3x^2)^2
try the second one, let me know what you got 
you might be surprised at the answer to #2, unless you note that
sin^2/(1+cos) = (1cos^2)/(1+cos) = 1cos
no need for quotient rule or chain rule here.