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

Redeem

PS: Number properties- factors

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 287
Joined: Fri Mar 23, 2012 12:33 am
Location: Pune,India
Thanked: 60 times
Followed by:6 members

PS: Number properties- factors

by GMAT Kolaveri » Fri Apr 20, 2012 8:57 pm
If x and y are integers such that x+y = 14, which of the following could be their product?

-72
-40
9
21
32

Need to know alternate methods of solving this problem
Regards and Thanks,
Vinoth@GMAT Kolaveri
https://www.facebook.com/GmatKolaveri
https://gmatkolaveri.tumblr.com/

Click the thank you button if you like my reply :)
Top
Source: — Problem Solving |
Legendary Member
Posts: 1084
Joined: Fri Apr 15, 2011 2:33 pm
Thanked: 158 times
Followed by:21 members

by pemdas » Fri Apr 20, 2012 10:37 pm
P=answer choice, then xy=P and x+y=14 --> x=14-y
y(14-y)=P, y^2-14y+P=0. By FOIL-ing we get y_1+y_2=-14 and y_1*y_2 equivalent to P :)
Listing options: 1-15, 2-16, 3-17, 4-18 <-- success and pick a
GMAT Kolaveri wrote:If x and y are integers such that x+y = 14, which of the following could be their product?

-72
-40
9
21
32

Need to know alternate methods of solving this problem
Success doesn't come overnight!
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Sat Apr 21, 2012 2:15 am
GMAT Kolaveri wrote:If x and y are integers such that x+y = 14, which of the following could be their product?

-72
-40
9
21
32

Need to know alternate methods of solving this problem
Use the answers.
Look for a factor pair with a sum of 14.

A: -72
Factors of 72: 8*9, 6*12, 4*18...
We can stop there.
If x=18 and y=-4, then xy=-72 and x+y=18+(-4) = 14.

The correct answer is A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Post new topic Post Reply
• Page 1 of 1