Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 9 Quadratic Relations and Conic Sections - 9.2 Graph and Write Equations of Parabolas - 9.2 Exercises - Skill Practice - Page 623: 23

Answer

The parabola, focus and directrix should be rotated by $90$ degrees clockwise.

Work Step by Step

$\bf{Step\text{ }1}$ Bring the equation in standard form: $$\begin{align*} -6x+y^2&=0&&\text{Write the original equation.}\\ y^2&=6x&&\text{Add }6x\text{ to each side}. \end{align*}$$ $\bf{Step\text{ }2}$ We identify the focus, directrix and axis of symmetry. The equation has the form $y^2=4px$, where $p=1.5$. The $\bf{focus}$ is $(p,0)$ or $\left(1.5,0\right)$. The $\bf{directrix}$ is $x=-p$ or $x=-1.5$. Because $y$ is squared, the $\bf{axis\text{ } of\text{ }symmetry}$ is the $x$-axis. $\bf{Step\text{ }3}$ We $\bf{draw}$ the parabola by making a table of values and plotting points. As $p>0$, the parabola opens to the right. So we will use only positive $x$-values. \[ \begin{array}{cccccc} x &|& 1 &|& 2 &|& 3 &|& 4 &|& 5 &|&\\ y &|& \pm 2.45 &|& \pm 3.46 &|& \pm 4.24 &|& \pm 4.90 &|& \pm 5.48 &|&\\ \end{array}\] The mistake in the given graph is that the parabola, the focus and the directrix should be rotated by $90$ degrees clockwise. Here is the correct graph:
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.