There are two lines with slopes m and n. Are they : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 23 Jan 2017, 20:03

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# There are two lines with slopes m and n. Are they

Author Message
Intern
Joined: 19 Mar 2007
Posts: 18
Followers: 0

Kudos [?]: 3 [0], given: 0

There are two lines with slopes m and n. Are they [#permalink]

### Show Tags

31 Mar 2008, 13:36
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

There are two lines with slopes m and n. Are they perpendicular?

1. mn =-1
2. m > 0 and n < 0
Intern
Joined: 31 Mar 2008
Posts: 14
Followers: 0

Kudos [?]: 1 [0], given: 0

### Show Tags

31 Mar 2008, 13:50
There are two lines with slopes m and n. Are they perpendicular?

1. mn =-1

m = -1/n
slope of m is the negative reciprocal of n. negative reciprocals are perpendicular.

2. m > 0 and n < 0

irrelevant

Only (1) is needed
Senior Manager
Joined: 01 Feb 2005
Posts: 274
Followers: 2

Kudos [?]: 92 [0], given: 1

### Show Tags

31 Mar 2008, 17:07

There are two lines with slopes m and n. Are they perpendicular?

1. mn =-1
2. m > 0 and n < 0

From 1 we know that the product of slopes = -1. Therefore 1 is sufficient (AD)

2 is insufficient M could be 1 and n could be -1. Therefore m.n = -1 (Perpendicular) But what if m = 2 and n = -1 (insufficient).

Hence A is the best answer
Re: Coordinate geometry   [#permalink] 31 Mar 2008, 17:07
Display posts from previous: Sort by