posted by albert on .
By applying in turn the Composite and Quotient Rules, find derivative and second derivative.
f '(x) = (e^x + e^-x)/(e^x - e^-x)
= e^-x(e^(2x) + 1)/(e^-x(e^(2x) - 1)
= (e^(2x) + 1)/(e^(2x) -1)
now use the quotient rule to get the second derivative,
let me know what you got.