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

Redeem

Goemetry Q

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 33
Joined: Tue Nov 27, 2007 2:35 am

Goemetry Q

by dev.gavande » Tue Oct 04, 2011 12:05 am
If equation encloses a certain region on the coordinate plane, what is the area of this region?
"¢ 20
"¢ 50
"¢ 100
"¢ 200
"¢ 400

My answer is 100, its wrong. Need to know why.
Top
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 496
Joined: Tue Jun 07, 2011 5:34 am
Thanked: 38 times
Followed by:1 members

by sl750 » Tue Oct 04, 2011 12:06 am
Is this question in its entirety?
Top

GMAT/MBA Expert

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

by Anurag@Gurome » Tue Oct 04, 2011 12:06 am
dev.gavande wrote:If equation encloses a certain region on the coordinate plane, what is the area of this region?
"¢ 20
"¢ 50
"¢ 100
"¢ 200
"¢ 400

My answer is 100, its wrong. Need to know why.
What is the equation?
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
Senior | Next Rank: 100 Posts
Posts: 33
Joined: Tue Nov 27, 2007 2:35 am

by dev.gavande » Tue Oct 04, 2011 12:11 am
Sorry did'nt see preview. here is the equation
If equation |x/2|+|y/2|=5 encloses a certain region on the coordinate plane, what is the area of this region?
"¢ 20
"¢ 50
"¢ 100
"¢ 200
"¢ 400
Top

GMAT/MBA Expert

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

by Anurag@Gurome » Tue Oct 04, 2011 12:16 am
dev.gavande wrote:Sorry did'nt see preview. here is the equation
If equation |x/2|+|y/2|=5 encloses a certain region on the coordinate plane, what is the area of this region?
"¢ 20
"¢ 50
"¢ 100
"¢ 200
"¢ 400
|x/2| + |y/2| = 5 implies |x| + |y| = 10

If you split this into the 4 possible values:

x + y = 10, x - y = 10, -x - y = 10, -x + y = 10
The above equations are lines with slopes -1, 1, -1, and 1 respectively.

If we graph this, it will be a rhombus with center at the origin.
Total Area = 1/2 (20 * 20) = 200

The correct answer is D.
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
Senior | Next Rank: 100 Posts
Posts: 33
Joined: Tue Nov 27, 2007 2:35 am

by dev.gavande » Tue Oct 04, 2011 12:53 am
I am sorry i am not getting this... till the slopes its fine.
how did you figure it will be a rhombus?
Top
Legendary Member
Posts: 2789
Joined: Tue Jul 26, 2011 12:19 am
Location: Chennai, India
Thanked: 206 times
Followed by:43 members
GMAT Score:640

by GmatKiss » Tue Oct 04, 2011 5:49 am
Same doubt here! and how is it 1/2 (20 * 20)?!
Waiting for clarifications.

TIA,
GK
Top
Legendary Member
Posts: 966
Joined: Sat Jan 02, 2010 8:06 am
Thanked: 230 times
Followed by:21 members

by shankar.ashwin » Tue Oct 04, 2011 11:26 am
You get these 4 equations removing the modulus

x + y = 10, x - y = 10, -x - y = 10, -x + y = 10

Plot the lines in a graph, You get (0,10) (0.-10) (10,0) (-10,0) - A diamond shaped figure with center at origin. (Sub x=0 or y=0 in all the equations and plot the extreme values)

The 2 diagonals are 20 units and all 4 sides are equal, You could find the area of the rhombus.
Top
Post new topic Post Reply
• Page 1 of 1