Hey my teacher worked this problem out the other day and I wrote it down but now im having trouble understanding it. This is what he wrote. Can someone verify if it is correct.(adsbygoogle = window.adsbygoogle || []).push({});

[tex]y=\frac{e^{2u}}{e^u+e^{-u}}[/tex]

[tex]y'=\frac{(e^u+e^(-u))(e^(2u))(2)-e^(2u)(e^u+e^-u(-1))}{(e^u+e^-u)^2}[/tex]

[tex]y'=\frac{e^(2u)[2e^u+2e^-u-e^u+e^-u]}{(e^u+e^-u)^2}[/tex]

[tex]y'=\frac{e^(2u)[e^u+3e^-u]}{(e^u+e^-u)^2}[/tex]

What I don't understand is how in the step after the quotient rule was used there is in brackets [tex]-e^u+e^-u[/tex] Doesn't multiplying it by-1 make it [tex]e^u+e^-u[/tex]

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# Finding the derrivative

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