College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 7 - Review Exercises - Page 540: 6

Answer

Parabola. Vertex: $ \quad (2,-2)$ Focus: $ \displaystyle \quad (2,-\frac{3}{2})$ Directrix:$ \displaystyle \quad y=-\frac{5}{2}$

Work Step by Step

One variable is squared, the other is not: Parabola. Complete the square on the LHS $x^{2}-4x+4=2y+4$ $(x-2)^{2}=2(y+2)$ $(x-2)^{2}=4(\displaystyle \frac{1}{2})(y+2)$ $a=\displaystyle \frac{1}{2}$ Table 2: $\begin{array}{lll} {\text{Focus}}&{\text{Directrix}}&{\text{Equation}}\\\hline {(h,k+a)}&{y=k-a}&{(x-h)^{2}=4a(y-k)}\\ \end{array}$ Vertex: $ \quad (h,k)=(2,-2)$ Focus: $ \displaystyle \quad (h,k+a)=(2,-\frac{3}{2})$ Directrix: $ \displaystyle \quad y=k-a \quad \Rightarrow\quad y=-\frac{5}{2}$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.