Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 11 - Review - Exercises - Page 833: 7

Answer

(a) Vertex: $V(-2,2)$ Focus: $F(-1,2)$ Directrix: $x=-3$ (b)

Work Step by Step

Equation of a parabola with horizontal axis and vertex at $(h,k)$: $(y-k)^2=4p(x-h)$ $(y-2)^2=4(x+2)$ $(y-2)^2=4[x-(-2)]$ $h=-2$ $k=2$ Vertex: $V(h,k)=V(-2,2)$ $4p=4$ $p=1$ The given equation can be obtained by shifting $y^2=4x$ left 2 units and upward 2 units. In this equation: Focus: $F(p,0)=F(1,0)$ Directrix: $y=-p=-1$ Now, shift the focus and the directrix 2 units to the left and 2 units upward: Focus: $F(-1,2)$ Directrix: $x=-3$
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