See attachment
I was wondering if anyone could help me. I am really stuck on the following question.
A) How do you show that the derivative of :
f(x) = sech (x)
is:
-sech(x)tanh(x)
B) Find values of C and D so that Csech(Dx) is a solution of:
(d^2u)/(dx^2) - u + u^3 = 0
Any help would be greatly appreciated.