Hi,

I am trying to differentiate

(N*k/3)*[T-(Q/6.7)*arctan(6.7T/Q)]

with respect to T.

Apparently the answer is

(N*k/3)*[(6.7T/Q)^2 / 1 + (6.7T/Q)^2]

I am getting

(N*k/3)*[1/(1+(6.7T/Q)^2)]

Could someone give me breakdown of how this is done and perhaps point out where I have gone wrong?

Thanks

(P.S. sorry for not being able to use MATH)