Chapter 7, Conic Sections - Section 7.1 - Parabolas - 7.1 Exercises - Page 555: 45

$x^2=-40y$

Opens downwards. It is a parabola with vertical axis. Focus: $F(0,p)$ Vertex: $V(0,0)$ $p$ is a negative number because the focus is on the negative y-axis. The vertex is above the focus. Distance between the focus and the vertex: $0-p=-p$ $-p=10$ $p=-10$ Equation: $x^2=4py$ $x^2=4(-10)y$ $x^2=-40y$