Question: 1. Find the equation of the vertical plane perpendicular to the y-axis and through the point (2, 3, 4).
2. Which of the points P1 = (-3, 2, 15), P2 = (0, -10, 0), P3 = (-6, 5, 3) and P4 = (-4, 2, 7) is closest to P = (6, 0, 4)?
3. If the contours of g(x, y) are concentric circles, then the graph of g is a cone.