What is the sum? 3/x^2-9 +5/x+3
a) 8/x^2+x-6
b)5x-12/x-3
c)-5x / (x+3)(x-3)
d)5x-12 / (x+3)(x-3)

Prove (a) cosh2(x) − sinh2(x) = 1 and (b) 1 − tanh 2(x) = sech 2(x). solution (a) cosh2(x) − sinh2(x) = ex + e−x 2 2 − 2 = e2x + 2 + e−2x 4 − = 4 = . (b) we start with the identity proved in part (a): cosh2(x) − sinh2(x) = 1. if we divide both sides by cosh2(x), we get 1 − sinh2(x) cosh2(x) = 1 or 1 − tanh 2(x) = .

Which of the following contains a variable?

Use the elimination method to solve the systems of equations. choose the correct ordered pair. 7x+4y=39