Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 07 May 2015, 01:41

### 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 two points does the graph of

Author Message
TAGS:
Intern
Joined: 26 Jan 2008
Posts: 26
Followers: 0

Kudos [?]: 5 [0], given: 0

In the xy-plane, at what two points does the graph of [#permalink]  06 Sep 2008, 19:54
1
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
3. In the xy-plane, at what two points does the graph of y=(x+a)(x+b) intersect the x-axis?
a. A+b = -1
b. The graph intersects the y-axis at (0,-6)
Director
Joined: 12 Jul 2008
Posts: 518
Schools: Wharton
Followers: 16

Kudos [?]: 119 [2] , given: 0

Re: DS- graph problem [#permalink]  06 Sep 2008, 21:50
2
KUDOS
ttwang56 wrote:
3. In the xy-plane, at what two points does the graph of y=(x+a)(x+b) intersect the x-axis?
a. A+b = -1
b. The graph intersects the y-axis at (0,-6)

y = x^2 + (a+b)x + ab
Need to know values for a and b

(1) Insufficient
y = x^2 - x + ab --> ab = ?

(2) Insufficient
-6 = 0^2 + 0*(a+b) + ab
ab = -6

(1) and (2) Sufficient
a+b = -1
ab = -6

a = -3
b = 2
Current Student
Joined: 11 May 2008
Posts: 562
Followers: 7

Kudos [?]: 55 [0], given: 0

Re: DS- graph problem [#permalink]  07 Sep 2008, 09:54
is it reqd to know abt parabolas and their formulas for the GMAT?
Director
Joined: 12 Jul 2008
Posts: 518
Schools: Wharton
Followers: 16

Kudos [?]: 119 [0], given: 0

Re: DS- graph problem [#permalink]  07 Sep 2008, 10:34
arjtryarjtry wrote:
is it reqd to know abt parabolas and their formulas for the GMAT?

it isn't, but you don't need to know that the equation describes a parabola to be able to solve the problem
SVP
Joined: 28 Dec 2005
Posts: 1583
Followers: 2

Kudos [?]: 88 [0], given: 2

Re: DS- graph problem [#permalink]  19 Sep 2008, 13:06
C ... intercepts happen at -a and -b, and thats what we need to find.

from stat 1, we cant determine individual values, since any number of combinations would satisfy the inequality

from stat 2, we know that ab=6 (y intercept happens when x=0, so y=6=(0-a)(0-b))

Together, we have two equations and two unknowns, so we can solve
Re: DS- graph problem   [#permalink] 19 Sep 2008, 13:06
Similar topics Replies Last post
Similar
Topics:
90 In the xy-plane, at what two points does the graph of 17 20 Jan 2007, 23:36
In the xy-plane, at what two points does the graph of 1 08 Jun 2008, 11:43
In the xy-plane, at what two points does the graph of 3 07 Jun 2008, 17:13
In the xy-plane, at what two points does the graph of 11 07 Dec 2007, 06:43
In the xy-plane, at what two points does the graph of 7 04 Jul 2006, 02:03
Display posts from previous: Sort by