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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

XY Problem #2 OG 12 88

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 392
Joined: Thu Jan 15, 2009 12:52 pm
Location: New Jersey
Thanked: 76 times

by truplayer256 » Sun Oct 04, 2009 4:33 pm
x=3y-7

Re-write the above equation to slope intercept form (y=mx+b) where m is the slope.

(x+7)/3=y

m=1/3

m=y2-y1/x2-x1

1/3=k/3

1=k
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 162
Joined: Sun Aug 09, 2009 4:17 pm
Location: Minnesota
Thanked: 1 times

Correct

by EMAN » Sun Oct 04, 2009 6:15 pm
Good work. K=1 is correct. Might sound stupid, but how do you get m = 1/3 from y = (x+7)/3?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 392
Joined: Thu Jan 15, 2009 12:52 pm
Location: New Jersey
Thanked: 76 times

by truplayer256 » Sun Oct 04, 2009 6:24 pm
Good work. K=1 is correct. Might sound stupid, but how do you get m = 1/3 from y = (x+7)/3?
y=(x+7)/3 simplifies to y=x/3+7/3 and since y=mx+b, where m is the slope, we simply look for the number before the x in order to find the slope of the line. In this case, that number is 1/3. I hope this helps.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 162
Joined: Sun Aug 09, 2009 4:17 pm
Location: Minnesota
Thanked: 1 times

Explanation

by EMAN » Sun Oct 04, 2009 6:38 pm
So are we basically assuming x/3 is equivalent to 1/3 here? After finding 1/3, how do you find out k is 1. Sorry, I'm still trying to grasp the simple steps in between.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Community Manager
Posts: 1537
Joined: Mon Aug 10, 2009 6:10 pmFollowed by: 252 members
Thanked: 653 times

by papgust » Wed Oct 07, 2009 2:52 am
Rewriting the eqn. x=3y-7, you get x-3y=7.

Slope = -(co-efficient of x)/co-efficient of y

Here, slope m = -1/-3=1/3

Hope this helps!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 162
Joined: Sun Aug 09, 2009 4:17 pm
Location: Minnesota
Thanked: 1 times

X

by EMAN » Wed Oct 07, 2009 5:19 am
Still cannot understand why x is 1 or -1? Are we just assuming that b/c it has no coefficient.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 27
Joined: Thu Jul 23, 2009 6:29 am
Thanked: 3 times

Re: X

by aa2kash » Wed Oct 07, 2009 5:31 am
EMAN wrote:Still cannot understand why x is 1 or -1? Are we just assuming that b/c it has no coefficient.
@Eman :

As you already know that a line equation is in the form of ax+by+c=0
here: a is the co-efficient of x
b is the co-efficient of y
So if you look at the line equation given to us
x-3y -7=0
this can be rewritten as 1*x + (-3)*y -7=0
And Slope is = -(co-efficient of x)/co-efficient of y
= -(1)/(-3)= 1/3

Hope it clarifies your doubt.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1