Asubstance decays so that the amount a of the substance left after t years is given by: a = a 0 · (0.75) t , where a 0 is the original amount of the substance. what is the amount of time it takes for there to be one-third of this substance left, rounded to the nearest tenth of a year?

Determine whether the following statements are true and give an explanation or counterexample. bold a. when using the shell method, the axis of the cylindrical shells is parallel to the axis of revolution. bold b. if a region is revolved about the y-axis, then the shell method must be used. bold c. if a region is revolved about the x-axis, then in principle it is possible to use the disk/washer method and integrate with respect to x or the shell method and integrate with respect to y.

Inez has a phone card. the graph shows the number of minutes that remain on her phone card a certain number of days.

Two triangles can be formed with the given information. use the law of sines to solve the triangles. b = 49°, a = 16, b = 14