Which is an equation of the given line in standard form? (-4, -1) and (1 1/2, 2) a.) -11x + 6y= -13 b.) -6x + 11y = 13 c.) -6x + 11y= -13 d.) -6x + 7y= -17

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) = .