What kind of function best models each situation? write linear, quadratic, exponential, trigonometric, or piecewise.

1. a radioactive element has a half-life of 20 minutes. a sample contains 66 g of the element. a function models the amount of the sample remaining as a function of time.

2. a function models the nth term in the following sequence: 8.5, 5, 1.5, -2, -5.5,

and you. much appreciated.