A hobby store is having a sale on picture frames buy 3 get the 4th one at 75% off. What is an expression to represent total cost of 4 frames.

The two-way frequency table below shows data on playing a sport and playing a musical instrument for students in a class.

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) = .

How would you describe the difference between the graphs of f(x) = 2x2 and g(x) = -2x2?