#y=(tan x)^2*(sec x)^5" "sec x=1/cos x" ; "sec^5 x=1/cos^5 x#
#y=(tan^2 x)/(cos^5 x) #
#(d y)/(d x)=((tan^2 x)^'*cos^5 x-(cos^5 x)^' *tan^2 x)/(cos^5 x)^2#
#(tan^2 x)^'=2 tan x(1+tan ^2 x)#
#(cos^5 x)'=-5sin x cos^4 x#
#(d y)/(d x)=((2 tan x(1+tan ^2 x)*cancel(cos^5 x))-((-5 sin x cancel(cos ^4 x))*tan^2 x))/(cancel(cos^10 x)#
#(d y)/(d x)=((2 tan x(1+tan^2 x)cos x)-((-5sin x)*tan^2 x))/(cos^6 x)#
#(d y)/(d x)=(2tan x(1+tan^2 x)cos x+5sin x tan^2 x)/(cos^6 x)#
#(d y)/(d x)=(5sin x tan^2 x)/(cos^6 x)+(2 tan x(1+tan^2 x)cos x)/(cos^6 x)#
#(d y)/(d x)=(5sin x tan^2 x)/(cos^6 x)+(2 tan x(1+tan^2 x)cos x)/(cos^6 x)#
#(d y)/(d x)=(5sin x tan^2 x)/(cos^6 x)+(2 tan x(1+tan^2 x))/(cos^5 x)#