Find all School-related info fast with the new School-Specific MBA Forum
Learn more about the recent changes... close

It is currently 19 May 2013, 08:54
Customize  |  Hide

Search
Register
New posts
Unanswered

In the xy plane line m has the equation 4x + y = k. Line n

  Question banks Downloads My Bookmarks Reviews  
  Oldest Best Reply
Search for:
 
Print view
First unread post
Author Message
TAGS:
1 KUDOS received
Intern
Intern
Joined: 06 Mar 2012
Posts: 2
Followers: 0

Kudos [?]: 1 [1] , given: 0

In the xy plane line m has the equation 4x + y = k. Line n [#permalink] New post 06 Mar 2012, 10:37
1
This post received
KUDOS
00:00

Question Stats:

78% (03:16) correct 21% (03:52) wrong based on 3 sessions
In the xy plane line m has the equation 4x + y = k. Line n passes through the origin and is perpendicular to line m. If point p has the coordinates (r, r+1) and is on both line n and m what is the value of r?

A. -4/3
B. 1/4
C. -4
D. 3/4
E. 4/3

Can anybody help me with this problem?! I really have no idea how to attack this problem..
Thanks!!
[Reveal] Spoiler: OA
Intern
Intern
Joined: 13 Jan 2012
Posts: 4
Followers: 0

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

Re: Coordinate GGeometry [#permalink] New post 06 Mar 2012, 11:46
This is an interesting problem, and I haven't solved it either as I am still learning this stuff. so far I've gotten about 3 different wrong answers.

I re wrote the equation of the line M: to Y=-4x + k

Given that N is perpendicular I believe the slope should be the opposite of M's, and it says it passes through the origin so I believe its intercept is 0 so i re wrote line N: to Y=4x + 0

the only point where these two lines share is there intersection where line M=N

-4x+k = 4x+0
k = 8x

x= k/8

plug into either equation to solve for Y = K/2

intersection point is K/8, K/2

since this is equal to P, k/8= R and K/2 = r+1

I think I must have made a mistake because after this point I get various answers that are wrong.

K/8 = K/2 + 1

I solve for K = - 8/3

then I plug back in to solve for R given R= k/8 thus

-8/3 divided by 8

and I get -1/3 = r

an exact difference of positive one... what did i do wrong?
1 KUDOS received
GMAT Club team member
User avatar
Joined: 02 Sep 2009
Posts: 11515
Followers: 1791

Kudos [?]: 9533 [1] , given: 826

GMAT Tests User CAT Tests
Top Member of the Month
Re: Coordinate GGeometry [#permalink] New post 06 Mar 2012, 12:01
1
This post received
KUDOS
In the xy plane line m has the equation 4x + y = k. Line n passes through the origin and is perpendicular to line m. If point p has the coordinates (r, r+1) and is on both line n and m what is the value of r?
A. -4/3
B. 1/4
C. -4
D. 3/4
E. 4/3

The equation of line m is y=-4x+k. Now, since line n is perpendicular to line m, then its slope is negative reciprocal of the slope of line m, so the slope of n is 1/4. Next, as line n passes through the origin (0, 0) and has the slope of 1/4 then its equation is y=1/4*x.

Point (r, r+1) lies on line n means that (r+1)=1/4*r --> r=-4/3.

Answer: A.

For more on this subject check Coordinate Geometry chapter of Math Book: math-coordinate-geometry-87652.html

Hope it helps.
_________________

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!


What are GMAT Club Tests?
25 extra-hard Quant Tests

Find out what's new at GMAT Club - latest features and updates

Intern
Intern
Joined: 06 Mar 2012
Posts: 2
Followers: 0

Kudos [?]: 1 [0], given: 0

Re: In the xy plane line m has the equation 4x + y = k. Line n [#permalink] New post 07 Mar 2012, 03:05
Thanks a lot :)

I was stuck at that point, that k=o, because passing through the origin
Re: In the xy plane line m has the equation 4x + y = k. Line n   [#permalink] 07 Mar 2012, 03:05
    Similar topics Author Replies Last post
Similar
Topics:
 New posts If Line K in the xy-plane has equation y=mx+b, where m and b carsen 8 21 May 2004, 00:55
New posts 2 If Line k in the xy-plane has equation y = mx + b, where m nikhilpoddar 6 01 Oct 2008, 01:51
New posts If Line k in the xy-plane has equation y = mx + b, where m KocharRohit 7 17 Nov 2009, 20:53
New posts EXPERTS_POSTS_IN_THIS_TOPIC If Line k in the xy-plane has equation y = mx + b, where m udaymathapati 2 02 Sep 2010, 12:52
New posts 4 EXPERTS_POSTS_IN_THIS_TOPIC If Line k in the xy-plane has equation y = mx + b, where m TomB 8 26 Mar 2012, 13:56
Display posts from previous: Sort by

In the xy plane line m has the equation 4x + y = k. Line n

  Question banks Downloads My Bookmarks Reviews  
Print view
First unread post

Moderators: Bunuel, VeritasPrepKarishma, IanStewart

Search for:


cron

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®.

Main navigation

GMAT Resources

Partners

MBA Resources

www.gmac.com|www.mba.com