What should be done to both sides of the equation in order to solve w - 9 = 15? Add 9 .
Subtract 9 .
Subtract 15.
Add 15.

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) = .

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Precalculus question, image attached.