Differentiate \frac{e^{8u}-e^{-8u}}{e^{8u}+e^{-8u}} ?

Differentiate \frac{e^{8u}-e^{-8u}}{e^{8u}+e^{-8u}} ?

2 Answers
Jun 14, 2018

f'(u)=(32*e^(16u))/(1+e^(16u))^2

Explanation:

Multiplying numerator and denominator by

e^(8u)
we get
f(u)=(e^(16u)-1)/(e^(16u)+1)
now we get by the Quotient and chain rule

f'(u)=((e^(16u)*16*(e^(16u)+1)-(e^(16u)-1)*e^(16u)*16))/(e^(16u)+1)^2
simplifying we get the result above.

Jun 14, 2018

Please see the explanation below.

Explanation:

We know that

(e^(8u)-e^(-8u))/(e^(8u)+e^(8u))=tanh(8u)

Therefore, the derivative is

(tanh(8u))'=8sech^2(8u)

=8/cosh^2(8u)

=32/(e^(8u)+e^(-8u))^2

=(32e^(16u))/(e^(16u)+1)^2