Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 10 - Analytic Geometry - 10.1 Parabolas - 10.1 Exercises - Page 967: 34

Answer

$$\eqalign{ & {\text{Focus: }}\left( { - 2,7} \right) \cr & {\text{directrix: }}y = - 3 \cr & {\text{axis of symmetry: }}x = - 2 \cr} $$

Work Step by Step

$$\eqalign{ & {\left( {x + 2} \right)^2} = 20\left( {y - 2} \right) \cr & {\text{This equation is written in the form }}{\left( {x - h} \right)^2} = 4p\left( {y - k} \right){\text{ }} \cr & {\text{represents Parabola with horizontal axis of symmetry}} \cr & {\text{of Symmetry and Vertex }}\left( {h,k} \right). \cr & \underbrace {{{\left( {x + 2} \right)}^2} = 20\left( {y - 2} \right)}_{{{\left( {x - h} \right)}^2} = 4p\left( {y - k} \right){\text{ }}} \cr & {\text{Let }}k = 2,\,\,\,\,h = - 2 \cr & 4p = 20 \cr & p = 5 \cr & {\text{Focus}}\left( {h,p + k} \right){\text{ and directrix }}y = - p + k \cr & {\text{Axis of symmetry }}x = h \cr & {\text{Focus: }}\left( { - 2,5 + 2} \right) \cr & {\text{Focus: }}\left( { - 2,7} \right) \cr & {\text{directrix: }}y = - 5 + 2 \cr & {\text{directrix: }}y = - 3 \cr & {\text{axis of symmetry: }}x = - 2 \cr & \cr & {\text{Focus: }}\left( { - 2,7} \right) \cr & {\text{directrix: }}y = - 3 \cr & {\text{axis of symmetry: }}x = - 2 \cr} $$
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