Suppose a rock is thrown off of a bridge into the river 120 feet below. The height, h, in feet of the rock above the river is given by h = −16t2 + 84t + 120, where t is the time in seconds. How long does it take the rock to splash into the river below?

What is the distance between the points (2 -3) and (-6 4) on the coordinate plane

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) = .

Let f(x) = 5/x and g(x)=2x2+5x. what two numbers are not in the domain of f o g