Question 874623
{{{((e^(7x) - e^(-7x))^2 - (e^(7x) + e^(-7x))^2) / (e^(7x) + e^(-7x))^2
}}}

use the identity a^2-b^2= (a+b)(a-b)



{{{((e^(7x) - e^(-7x)) +(e^(7x) + e^(-7x)))(e^(7x) - e^(-7x) -e^(7x) - e^(-7x)) / (e^(7x) + e^(-7x))^2
}}}

{{{2e^(7x)*-2(e^(-7x))/(e^(7x) + e^(-7x))^2}}}


={{{(-4)/(e^(7x) + e^(-7x))^2}}}