Answer
Focus: $(0,-3)$
Directrix: $y=3$
Work Step by Step
Equation of a parabola with vertical axis and vertex at origin:
$x^2=4py$
$x^2=-12y$
$4p=-12$
$p=-3$
Focus: $F(0,p)=(0,-3)$
Directrix: $y=-p=3$
Precalculus: Mathematics for Calculus, 7th Edition
by Stewart, James; Redlin, Lothar; Watson, Saleem
Published by
Brooks Cole
ISBN 10:
1305071751
ISBN 13:
978-1-30507-175-9
Chapter 11 - Review - Test - Page 835: 1
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