Describe the graph of the equation. r = -3i+(1 - t²)j +t k O It is a parabola in the plane x = -3, with vertex at (-3, 1, 0), opening to the 'left' (negative y). O It is a parabola in the plane x = -3, with vertex at (-3, 0, 1), opening to the 'right' (positive y). O It is a parabola in the plane : = -3, with vertex at (1, 0, - 3), opening to the 'left' (negative y). %3D O It is a parabola in the plane : = -3, with vertex at (1, 0, - 3), opening to the 'right' (positive y). O It is a parabola in the plane x = -3, with vertex at (-3, 1, 0), opening up (positive :).

1 3-5

Sand is being dumped from a hopper railcar at a rate of 40 cubic feet per minute. It forms a pile in the shape of a right circular cone whose base diameter and height are always equal to each other (both are growing larger as more sand is dumped). How fast is the base diameter increasing when the base is 18 feet long? Round your answer to three decimal places. ft/min

12.6

6