In the xy-plane at what points does the graph of y : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 20 Jan 2017, 17:27

### 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

# In the xy-plane at what points does the graph of y

Author Message
Director
Joined: 10 Feb 2006
Posts: 658
Followers: 3

Kudos [?]: 461 [0], given: 0

In the xy-plane at what points does the graph of y [#permalink]

### Show Tags

25 Nov 2007, 19:23
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

In the xy-plane at what points does the graph of y =(x+a)(x+b) intersect the x-axis?

(1). a + b = -1
(2). The graph intersect the yaxis ast (0,-6)

Solution :

Wait for you solution. thanks
_________________

GMAT the final frontie!!!.

CEO
Joined: 17 Nov 2007
Posts: 3589
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
Followers: 548

Kudos [?]: 3559 [0], given: 360

### Show Tags

25 Nov 2007, 22:20
C

y =(x+a)(x+b) - parabola that intersect x-axis at points (-a,0) and (-b,0)
Therefore, we should known both a and b.

1. a + b = -1 (-3,2) and (-2,1) match equation - insufficient
2. The graph intersect the yaxis ast (0,-6) means -6=(0+a)(0+b) ==> ab=-6
(-3,2) and (1,-6) match equation - insufficient

1&2. a + b = -1 and ab=-6 ==> solution: -3 and 2 sufficient
Director
Joined: 22 Aug 2007
Posts: 567
Followers: 1

Kudos [?]: 50 [0], given: 0

### Show Tags

25 Nov 2007, 23:08
also for C,

1) INSUFF

a+b=-1-------------> (a,b) could be 0,-1 ; -5,4 ; or vice versa

2) INSUFF

ab=-6--------------> (a,b) could be 1,-6 ; -2;3 ; or vice versa

both) SUFF

a= -1-b

ab= (-1-b)b
b^2-b-6=0

b=2 or b=-3

b=2 a= -3
b=-3 a=2

in any case parabola intersects x axis at (3,0) and (-2,0)
SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 147 [0], given: 2

### Show Tags

16 Dec 2007, 13:03

statement 1 and 2 give multiple options, not sufficient.

With both, you can nail down that a=-2 and b=3
16 Dec 2007, 13:03
Display posts from previous: Sort by