BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Need expert help - Slope of a line

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 405
Joined: Thu Feb 10, 2011 1:44 amFollowed by: 1 member
Thanked: 3 times
by voodoo_child » Wed Aug 08, 2012 5:49 am
In the XY-Plane , is the slope of the line k equal to 0 ?

(1) The X- intercept of k is 0

(2) The y-intercept of k is 0.

Logically, OA E makes sense.

However, I need to understand what's wrong with the algebraic method. Please don't reply with an intuitive answer. There is no doubt about OA.

A
Let the equation of line be y=mx+c


1) X intercept => 0=mx+c => x=-c/m; Now if the x-intercept =0; it means that m could be either infinity or a non-zero. I believe that "Infinity/Infinity" is undefined. Hence, m will not be equal to Zero. No. This doesn't make sense. What am I missing here?

2) Y intercept => y= c =0; therefore, y=mx; Not sufficient.

1 and 2) x intercept = 0 and y-intercept = 0=> c=0 and c/m=0 => m is not equal to zero.

It's crazy, but I am a bit lost....

Thoughts?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Wed Aug 08, 2012 6:03 am
voodoo_child wrote:Hence, m will not be equal to Zero. No. This doesn't make sense. What am I missing here?
If we consider the equation of the line as y = mx + c,
Then from statement 1, we can conclude either of the following,
  • 1. c = 0 and m = anything
    • Note that for c = 0, m can be equal to zero. Which is possible when the line is nothing but the X-axis.
    2. c = anything and m = infinity
Hence, slope of the line may or may not be equal to zero.

Taking both statements together, c = 0 and -c/m = 0. As c = 0, -c/m is always equal to zero regardless of the value of m. Hence, m may or may not be equal to zero.

Hence, both statements together are also not sufficient.

The correct answer is E.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 405
Joined: Thu Feb 10, 2011 1:44 amFollowed by: 1 member
Thanked: 3 times

by voodoo_child » Wed Aug 08, 2012 8:21 am
Anurag@Gurome wrote:
  • Note that for c = 0, m can be equal to zero. Which is possible when the line is nothing but the X-axis.
Anurag,
thanks for your reply. However, we are given that x-intercept = 0 => c/m = 0. Therefore, if C = 0; how could m equal to 0? 0/0 is an indeterminate form. m CANNOT equal to zero.

X-axis doesn't have an x-intercept = 0. X-intercept on the x-axis could be anything from -infinity to +infinity.


Thoughts?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 349
Joined: Wed Sep 28, 2011 3:38 pmFollowed by: 54 members
Location: Austin, TX
Thanked: 236 times
GMAT Score:770

by GmatMathPro » Wed Aug 08, 2012 1:00 pm
voodoo_child wrote: 1) X intercept => 0=mx+c => x=-c/m; Now if the x-intercept =0; it means that m could be either infinity or a non-zero. I believe that "Infinity/Infinity" is undefined. Hence, m will not be equal to Zero. No. This doesn't make sense. What am I missing here?
The case of m=0 makes nonsense of your equation (x=-c/m) because the very step of going from mx=-c to x=-c/m assumes that m is not equal to 0. That is, dividing both sides of an equation by a quantity is ONLY valid if that quantity is not equal to zero. So your formula for x-intercept, by the nature of its existence, is not equipped to deal with the case m=0 because it is only valid in cases where m is NOT equal to zero.
Pete Ackley
GMAT Math Pro
Free Online Tutoring Trial
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1