Find all School-related info fast with the new School-Specific MBA Forum

It is currently 18 Sep 2014, 19:55

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the equation of the line that is perpendicular to

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2770
Location: New York City
Followers: 8

Kudos [?]: 232 [0], given: 4

GMAT Tests User
What is the equation of the line that is perpendicular to [#permalink] New post 21 Nov 2007, 05:28
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
What is the equation of the line that is perpendicular to line y=2x and passes through point (a,b)?

1. a = -b
2. a - b = 1

Please EXPLAIN your answer
Intern
Intern
avatar
Joined: 28 Aug 2007
Posts: 19
Location: London, United Kingdom
Followers: 1

Kudos [?]: 0 [0], given: 0

 [#permalink] New post 21 Nov 2007, 06:16
I'll give it a go...

The slope of a line perpendicular to another line is equal to minus the reciprocal of the slope of the line to which it is perpendicular.

Therefore the slope of the line perpendicular to y = 2x is -1/2

Therefore the equation of the perpendicular line is y = -1/2x + k

Statement 1: a = -b This is insufficient, as there are an infinite number of co-ordinates that match this criterion, e.g. (-1, 1), (1,-1), (2,-2), (-2,2), etc.

Statement 2: a - b = 1 This is insufficient, as again there are an infinite number of co-ordinates that match this criterion.

Statements 1 and 2 together: subsitute the equation in Statement 2 into the equation in Statement 1 and solve for b:
(1 + b) = -b
1 = -2b
b = -1/2

Subsitute into either equation to solve for a:

a = 1/2

Therefore the perpendicular line goes through co-ordinates (1/2; -1/2).

Substitute these co-ordinates into the equation of the perpendicular line and solve for k:

y = -1/2x + k

(-1/2) = -1/2(1/2) + k

-1/2 = -1/4 + k

- 2/4 + 1/4 = k

k = -1/4

Therefore equation of perpendicular line is y = -1/2x - 1/4

Therefore answer is C?
CEO
CEO
User avatar
Joined: 21 Jan 2007
Posts: 2770
Location: New York City
Followers: 8

Kudos [?]: 232 [0], given: 4

GMAT Tests User
 [#permalink] New post 23 Nov 2007, 09:51
OA is C. :lol:
  [#permalink] 23 Nov 2007, 09:51
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic What is the equation of a line perpendicular to lines Archit143 7 11 Nov 2012, 14:52
2 Experts publish their posts in the topic The line represented by equation y=x is the perpendicular pranav123 2 27 Oct 2012, 19:28
What is the equation of the line that is perpendicular to tkarthi4u 3 01 Oct 2009, 07:25
What is the equation of the line that is perpendicular to arjtryarjtry 7 02 Sep 2008, 01:42
What is the equation of the line that is perpendicular to mitul 2 29 Oct 2006, 19:16
Display posts from previous: Sort by

What is the equation of the line that is perpendicular to

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.