Buffy attends a night school, and the ages of the people in his study group are: 42, 55, 36, 41, 38, 33, and 46. What is the best estimate of the population mean for ages of night school attendees? Enter your answers rounded to the nearest tenth.

Give the equations of two different lines that are perpendicular to the line 3x + 4y = 7.

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 absolute value of -100000000000000?