Question

need help in calculus
http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=f4ccdf86d504bc91f8652fa6d7b76db6&title=Derivative%20Calculator&theme=blue&i0=1st&i1=tan^-1%28%28a%2Bx%29%2F%281-ax%29%29&podSelect=&includepodid=Input&podstate=Input__Step-by-step%20solution&showAssumptions=1&showWarnings=1

tan^-1((a+x)/(1-ax))

using substitution method differentiate it :'(
what should i substitute to get the answer ?????

Answer 1

i think i have to subtitute x with acos2theta

Answer 2

*phew* finally done it :)

Answer 3

try x= a than y

Answer 4

oh! how did u do it ?

Answer 5

lol @hartnn
there is a formula
tan^-1 x+ tan^-y = (x+y)/(1-xy)