It is currently 16 Dec 2017, 05:11

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Does the point of intersection of line y = kx + b and line x

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
VP
VP
avatar
Joined: 22 Nov 2007
Posts: 1078

Kudos [?]: 702 [0], given: 0

Does the point of intersection of line y = kx + b and line x [#permalink]

Show Tags

New post 15 Mar 2008, 10:52
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

50% (00:00) correct 50% (00:22) wrong based on 10 sessions

HideShow timer Statistics

Does the point of intersection of line y = kx + b and line x = ky + b have a negative x-coordinate?
1. k > 0, b > 0
2. k > 1

Kudos [?]: 702 [0], given: 0

Senior Manager
Senior Manager
avatar
Joined: 15 Aug 2007
Posts: 252

Kudos [?]: 73 [0], given: 0

Schools: Chicago Booth
Re: Ds coordinate geo [#permalink]

Show Tags

New post 15 Mar 2008, 11:23
C

Solving for x.. x= b(k+1)/(1-k^2)

1: can't tell what sign 1-k^2 is (k could be 0<k<1 or k=1 or k>1)
2: 1-k^2 is negative, but final sign depends on b's sign

combined - denominator is negative and numerator is positive, so x-coordinate must be negative.

Kudos [?]: 73 [0], given: 0

Manager
Manager
avatar
Joined: 15 Mar 2008
Posts: 50

Kudos [?]: 34 [0], given: 0

Re: Ds coordinate geo [#permalink]

Show Tags

New post 15 Mar 2008, 16:14
marcodonzelli wrote:
Does the point of intersection of line y = kx + b and line x = ky + b have a negative x-coordinate?
1. k > 0, b > 0
2. k > 1


Yes; the x-coordinate will be negative.
y= kx + b-------1

y= x/k - b/k-----2

Since the 2 equations have inverse slopes, they must represent perpendicular lines.
Take equation 1 first.
If y= 0, x= -b/k; If x= 0, y= b. Joining these 2 points, one gets a line going from -x-coordinate to +y coordinate. Now, if you plot the 2nd equation similarly, you find that when
x = 0, y = -b/k and when y = 0, x = b. On plotting these points it is seen that the 2 lines will intersect in the 3rd quadrant. Thus, x is negative.

Kudos [?]: 34 [0], given: 0

Senior Manager
Senior Manager
User avatar
Joined: 03 Mar 2010
Posts: 414

Kudos [?]: 371 [0], given: 22

Schools: Simon '16 (M)
Re: Ds coordinate geo [#permalink]

Show Tags

New post 21 Sep 2011, 04:32
Two line
y=kx+b ------1
y=x/k - b/k -------2
Subtracting 2 from 1
0=kx + b - (x/k - b/k)
0=kx - x/k + b + b/k
b/k -b = -kx + x/k
b(1/k + 1) = x(1/k - k)
b(1+k)/k = x[1-k^2/k]
b(1+k) = x(1-k^2)
b(1+k) = x(1+k)(1-k)
b = x(1-k)
x= b/(1-k)

1-k does the trick because even if k>0, it can be +ve or -ve thus making x +ve or -ve.

OA C.
_________________

My dad once said to me: Son, nothing succeeds like success.


Last edited by jamifahad on 22 Sep 2011, 00:42, edited 1 time in total.

Kudos [?]: 371 [0], given: 22

VP
VP
avatar
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1268

Kudos [?]: 292 [0], given: 10

Re: Ds coordinate geo [#permalink]

Show Tags

New post 21 Sep 2011, 22:02
by solving - y= 1/k x -b/k = kx + b

thus x = b/ 1-k

a not sufficient since k > 1 is not known.

b not sufficient since b is not known.

a+b

sufficient, x is negative.

C is it.
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Kudos [?]: 292 [0], given: 10

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 42630

Kudos [?]: 135805 [0], given: 12714

Re: Does the point of intersection of line y = kx + b and line x [#permalink]

Show Tags

New post 24 Nov 2017, 08:08
marcodonzelli wrote:
Does the point of intersection of line y = kx + b and line x = ky + b have a negative x-coordinate?
1. k > 0, b > 0
2. k > 1


PROPER VERSION OF THIS QUESTION IS DISCUSSED HERE: https://gmatclub.com/forum/if-k-does-no ... 89958.html
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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. ,11 Mixed Questions, 12 Fresh Meat

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., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Kudos [?]: 135805 [0], given: 12714

Re: Does the point of intersection of line y = kx + b and line x   [#permalink] 24 Nov 2017, 08:08
Display posts from previous: Sort by

Does the point of intersection of line y = kx + b and line x

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.