Question 912958

re TY
Yes, practice is good.
Recommend carefully keeping things 'intact' until You go in 'for the finish"
a) 
coshx = (e^x + e^(-x))/2 
-sinhx = <u>-(e^x - e^(-x))/2)</u>
cosh x - sinh x  = 2(e^(-x))/2) = e^(-x )
............
b)f(t) = csch t(1- ln csch t) 
f' = -csch(t)coth (t) - [-csch(t)coth (x)ln(csch(t) + csch(t)( -csch(t)coth (x)/csch(t)] 
 -csch(t)coth (t) +csch(t)coth (x)ln(csch(t) + csch(t)coth (x) 
 f' = csch(t)coth (t)ln(csch(t)