) If x represents the unknown part, which of the following shows a valid set of steps that can be used to find 15% of 30? 15 A. 30 B. 100 30 15 100 X 100x = 15.30 30x = 15 . 100 x = 4.5 x = 50 30 C. 15 100 D. 15 30 100 15x = 30 • 100 30x = 15 • 100 x=200 x = 50

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

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) = .

Bobs burgers bam has a special deal of 4 hamburgers for $6. at that rate, how much should it cost to buy 3 hamburgers?