Chapter 9 Quadratic Relations and Conic Sections - 9.2 Graph and Write Equations of Parabolas - 9.2 Exercises - Skill Practice - Page 623: 16

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The equation in standard form: $-y^2=18x\\y^2=-18x$ Identify the focus, directrix, and axis of symmetry. The equation has the form $y^2=4px$ where $p=-\frac{9}{2}$. The focus is $(-\frac{9}{2},0)$. The directrix is $x =-p=\frac{9}{2}$. Because $y$ is squared, the axis of symmetry is the x-axis. Find some values and plot points: $x=-1 \rightarrow y=\pm 4.24\\x=-2 \rightarrow y=\pm 6\\x=-3 \rightarrow y=\pm 7.35\\x=-4 \rightarrow y=\pm 8.49\\x=-5 \rightarrow y=\pm 9.49$