The instruction booklet for a DVD player says that the player uses about
0.4 kilowatt of electricity per hour. If
electricity costs $0.20 per kilowatt hour,
how much does it cost to run the player
for an hour?

The sales tax rate is 7.25%. how much tax in dollars is added on an item that costs $56.00? a. $4.06 b. $7.25 c. $14.50 d. $60.06

Jane moves from a house with 71 square feet of closet space to an apartment with 45.44 square feet of closet space. what is the percentage decrease of jane’s closet space?

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) = .