Chapter 9 Quadratic Relations and Conic Sections - 9.4 Graph and Write Equations of Ellipses - 9.4 Exercises - Skill Practice - Page 638: 38

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Given: $36y+x^2=0$ Identify the focus, directrix, and axis of symmetry. The equation has the form $x^2=4py$ where $p=\frac{-5}{4}$. The focus is $(\frac{-1}{2},0)$. The directrix is $x =-p=-9$. Because $x$ is squared, the axis of symmetry is the y-axis.