At the beginning of this month, royce had $171.26 in digital money. so far this month he has made deposits of $60.76, $29.79, and $89.31 into his account, while he has made withdrawals of $14.82, $46.79, and $55.52. how much digital money does royce have now?

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) = .