GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 25 Jun 2019, 13:16

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

If x^2 + 12x + 20 < 0, how many integer values can x be?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Manager
Manager
avatar
Joined: 10 Feb 2011
Posts: 107
If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 17 Mar 2011, 14:44
2
2
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

64% (01:28) correct 36% (01:35) wrong based on 118 sessions

HideShow timer Statistics


If x^2 + 12x + 20 < 0, how many integer values can x be?

(A) 6
(B) 7
(C) 8
(D) 9
(E) 10
Manager
Manager
avatar
Joined: 24 Nov 2010
Posts: 169
Location: United States (CA)
Concentration: Technology, Entrepreneurship
Schools: Ross '15, Duke '15
GMAT ToolKit User
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 17 Mar 2011, 15:32
banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10



x^2 + 12x + 20 < 0 --> (x+10)(x+2)<0 this will be true only when x<-2 and x> -10.

Ans = C
Manager
Manager
avatar
Joined: 18 Oct 2010
Posts: 68
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 17 Mar 2011, 19:30
the same solution and also found -8<a<-2 and
C is the answer
Retired Moderator
avatar
Joined: 20 Dec 2010
Posts: 1743
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 17 Mar 2011, 23:34
1
banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10


Sol:

x^2+12x+20 = x^2+10x+2x+20 = x(x+10)+2(x+10) = (x+2)(x+10)

(x+2)(x+10) < 0

Roots of x= -10,-2

Ranges; x<-10, -10<x<-2, x>-2

For x>-2, let's say x=0; (x+2)(x+10) = 2*10=20. It is a positive

Thus,
x>-2 is +ve
-10<x<-2 is -ve; alternated from previous
x<-10 is +ve; alternated from previous

For "<" sign, we must consider only -ves.

-10<x<-2 befits the value of x that satisfy the inequality.
x can be -9,-8,-7,-6,-5,-4,-3

Count=7

Ans: "B"
_________________
Senior Manager
Senior Manager
User avatar
B
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 491
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 18 Mar 2011, 08:34
fluke wrote:
banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10


Sol:

x^2+12x+20 = x^2+10x+2x+20 = x(x+10)+2(x+10) = (x+2)(x+10)

(x+2)(x+10) < 0

Roots of x= -10,-2

Ranges; x<-10, -10<x<-2, x>-2

For x>-2, let's say x=0; (x+2)(x+10) = 2*10=20. It is a positive

Thus,
x>-2 is +ve
-10<x<-2 is -ve; alternated from previous
x<-10 is +ve; alternated from previous

For "<" sign, we must consider only -ves.

-10<x<-2 befits the value of x that satisfy the inequality.
x can be -9,-8,-7,-6,-5,-4,-3

Count=7

Ans: "B"


how is x>-2?
i calculated x<-2, or x<-10.
_________________
Retired Moderator
avatar
Joined: 20 Dec 2010
Posts: 1743
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 18 Mar 2011, 09:21
Baten80 wrote:
fluke wrote:
banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10


Sol:

x^2+12x+20 = x^2+10x+2x+20 = x(x+10)+2(x+10) = (x+2)(x+10)

(x+2)(x+10) < 0

Roots of x= -10,-2

Ranges; x<-10, -10<x<-2, x>-2

For x>-2, let's say x=0; (x+2)(x+10) = 2*10=20. It is a positive

Thus,
x>-2 is +ve
-10<x<-2 is -ve; alternated from previous
x<-10 is +ve; alternated from previous

For "<" sign, we must consider only -ves.

-10<x<-2 befits the value of x that satisfy the inequality.
x can be -9,-8,-7,-6,-5,-4,-3

Count=7

Ans: "B"


how is x>-2?
No, x is not greater than -2.

Please read my post closely;
-10<x<-2 befits the value of x that satisfy the inequality.
x can be -9,-8,-7,-6,-5,-4,-3


Where I mentioned; "x>-2", I was just checking the side(+ve or -ve) of the inequality for the range where "x>-2"

i calculated x<-2, or x<-10.

I am afraid, this is not correct!!! It should be;
x<-2 AND x>-10



I have incorporated following method to calculate the range;

http://gmatclub.com/forum/inequalities-trick-91482.html

I humbly suggest you go through the same.
_________________
Manager
Manager
avatar
Joined: 24 Nov 2010
Posts: 169
Location: United States (CA)
Concentration: Technology, Entrepreneurship
Schools: Ross '15, Duke '15
GMAT ToolKit User
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 18 Mar 2011, 11:32
dreambeliever wrote:
banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10



x^2 + 12x + 20 < 0 --> (x+10)(x+2)<0 this will be true only when x<-2 and x> -10.

Ans = C



-10 to -2 exclusive on the number line leaves 7 integers not 8. have to quit committing this types mistakes!
Director
Director
avatar
Joined: 01 Feb 2011
Posts: 633
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 18 Mar 2011, 17:54
solving the inequality

one solution x < -10 , x>-2 , unlimited integers can be chosen for these

second solution x >-10 , x<-2 , 7 possible integers ( -9,-8,-7...-3)

Hence the answer is B.



banksy wrote:
27. (SC) If x^2 + 12x + 20 < 0, how many integer values can x be?
(A) 6
(B) 7
(C) 8
(D) 9
(E) 10
Retired Moderator
avatar
B
Joined: 16 Nov 2010
Posts: 1363
Location: United States (IN)
Concentration: Strategy, Technology
Reviews Badge
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 18 Mar 2011, 22:57
The question asks, for how many integer values of x:

(x+10)(x+2) < 0

so -10 < x -2

only 7 integers between -10 and -2, so answer is B.
_________________
Formula of Life -> Achievement/Potential = k * Happiness (where k is a constant)

GMAT Club Premium Membership - big benefits and savings
Retired Moderator
User avatar
P
Joined: 19 Mar 2014
Posts: 929
Location: India
Concentration: Finance, Entrepreneurship
GPA: 3.5
GMAT ToolKit User
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 19 Jun 2017, 14:37
After solving the equation, we get

(x+10)(x+2)<0

-10<x<-2

So, consider all the integer values within this range = -9, -8, -7, -6, -5, -4, -3

Which gives us 7 integer values, hence answer is B
_________________
"Nothing in this world can take the place of persistence. Talent will not: nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not: the world is full of educated derelicts. Persistence and determination alone are omnipotent."

Best AWA Template: https://gmatclub.com/forum/how-to-get-6-0-awa-my-guide-64327.html#p470475
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 11430
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?  [#permalink]

Show Tags

New post 27 Dec 2018, 03:06
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Bot
Re: If x^2 + 12x + 20 < 0, how many integer values can x be?   [#permalink] 27 Dec 2018, 03:06
Display posts from previous: Sort by

If x^2 + 12x + 20 < 0, how many integer values can x be?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne