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

 It is currently 18 Jan 2019, 17:19

### 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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• ### Free GMAT Strategy Webinar

January 19, 2019

January 19, 2019

07:00 AM PST

09:00 AM PST

Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
• ### FREE Quant Workshop by e-GMAT!

January 20, 2019

January 20, 2019

07:00 AM PST

07:00 AM PST

Get personalized insights on how to achieve your Target Quant Score.

# Math: Absolute value (Modulus)

Author Message
TAGS:

### Hide Tags

Intern
Joined: 25 Feb 2016
Posts: 11
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

23 Aug 2018, 01:37
How frequent or how many absolute value questions can we approximately expect on the GMAT? I understand there may not be a sure way to know or guess but just looking for an estimate based on past and present experiences.
Math Expert
Joined: 02 Sep 2009
Posts: 52285
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

23 Aug 2018, 02:12
1
1
onyx12102 wrote:
How frequent or how many absolute value questions can we approximately expect on the GMAT? I understand there may not be a sure way to know or guess but just looking for an estimate based on past and present experiences.

______________
I'd say 1 or 2.
_________________
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8792
Location: Pune, India
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

23 Aug 2018, 04:02
1
onyx12102 wrote:
How frequent or how many absolute value questions can we approximately expect on the GMAT? I understand there may not be a sure way to know or guess but just looking for an estimate based on past and present experiences.

Not more than a couple. The problem is that often GMAT likes to combine topics. So, you might have a geometry question which will make you use some basic absolute value concept such as area bounded by the graph of |x| + |y| = 4. So a basic understanding of all topics is a good idea even if you plan to ignore some topics.
_________________

Karishma
Veritas Prep GMAT Instructor

Intern
Joined: 29 Sep 2007
Posts: 2
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

01 Sep 2018, 14:16
Quote:
2. Solve new equations:
a) x−1=4x−1=4 --> x=5
b) −x+1=4−x+1=4 --> x=-3

3. Check conditions for each solution:
a) x=5x=5 has to satisfy initial condition x−1>=0x−1>=0. 5−1=4>05−1=4>0. It satisfies. Otherwise, we would have to reject x=5.
b) x=−3x=−3 has to satisfy initial condition x−1<0x−1<0. −3−1=−4<0−3−1=−4<0. It satisfies. Otherwise, we would have to reject x=-3.

So...just to clarify...the answer can either be 5 or -3?

Just need the clarification on what this is saying
Intern
Joined: 19 Jul 2018
Posts: 4
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

03 Sep 2018, 20:55
In the following example of 3-steps approach for complex problems

Example #1
Q.: |x+3|−|4−x|=|8+x||x+3|−|4−x|=|8+x|. How many solutions does the equation have?
Solution: There are 3 key points here: -8, -3, 4. So we have 4 conditions:

a) x<−8x<−8. −(x+3)−(4−x)=−(8+x)−(x+3)−(4−x)=−(8+x) --> x=−1x=−1. We reject the solution because our condition is not satisfied (-1 is not less than -8) Can any one please explain me how x<-8 because whenever I am doing it I am getting x>=-8 for both |8+x| and -|8+x|

b) −8≤x<−3−8≤x<−3. −(x+3)−(4−x)=(8+x)−(x+3)−(4−x)=(8+x) --> x=−15x=−15. We reject the solution because our condition is not satisfied (-15 is not within (-8,-3) interval.)

c) −3≤x<4−3≤x<4. (x+3)−(4−x)=(8+x)(x+3)−(4−x)=(8+x) --> x=9x=9. We reject the solution because our condition is not satisfied (-15 is not within (-3,4) interval.)

d) x≥4x≥4. (x+3)+(4−x)=(8+x)(x+3)+(4−x)=(8+x) --> x=−1x=−1. We reject the solution because our condition is not satisfied (-1 is not more than 4)
Manager
Joined: 11 Aug 2018
Posts: 90
Location: Pakistan
GPA: 2.73
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

22 Sep 2018, 02:50
IN Example #1
Q.: |x+3|−|4−x|=|8+x||x+3|−|4−x|=|8+x|. How many solutions does the equation have?
C condition has typo error
c) −3≤x<4−3≤x<4. (x+3)−(4−x)=(8+x)(x+3)−(4−x)=(8+x) --> x=9x=9. We reject the solution because our condition is not satisfied (-15 is not within (-3,4) interval.)

its not -15 but 9
_________________

If you like this post, be kind and help me with Kudos!

Cheers!

Manager
Joined: 28 Jun 2018
Posts: 72
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

29 Sep 2018, 05:26
chetan2u Hi, sorry I keep bugging you but your explanations are easiest to understand
Can you explain to me the "trick" mentioned in the post? I don't get it :/ What are we doing after finding the mid-point?
Math Expert
Joined: 02 Aug 2009
Posts: 7201

### Show Tags

29 Sep 2018, 09:02
hibobotamuss wrote:
chetan2u Hi, sorry I keep bugging you but your explanations are easiest to understand
Can you explain to me the "trick" mentioned in the post? I don't get it :/ What are we doing after finding the mid-point?

No problems. Pl keep asking questions and I would reply to each whenever I get time
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

Manager
Joined: 28 Jun 2018
Posts: 72
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

29 Sep 2018, 09:24
"Problem: 1<x<9. What inequality represents this condition?

A. |x|<3
B. |x+5|<4
C. |x-1|<9
D. |-5+x|<4
E. |3+x|<5
Solution: 10sec. Traditional 3-steps method is too time-consume technique. First of all we find length (9-1)=8 and center (1+8/2=5) of the segment represented by 1<x<9. Now, let’s look at our options. Only B and D has 8/2=4 on the right side and D had left site 0 at x=5. Therefore, answer is D."

This is the "trick" mentioned in the post, don't know what it means chetan2u
Intern
Joined: 28 Dec 2016
Posts: 3
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

20 Nov 2018, 12:54
gettinit wrote:
Let’s consider following examples,

Example #1 I am not understanding this example and really struggling with modulus? Can someone please elaborate and explain in further detail? From this post I can't see how I would use this on every modulus problem?
Q.: $$|x+3| - |4-x| = |8+x|$$. How many solutions does the equation have?
Solution: There are 3 key points here: -8, -3, 4. So we have 4 conditions:

a) $$x < -8$$. $$-(x+3) - (4-x) how did we get -(x+3) here?= -(8+x)$$ --> $$x = -1$$. We reject the solution because our condition is not satisfied (-1 is not less than -8)

b) $$-8 \leq x < -3$$. $$-(x+3)-(4-x) =+ (8+x)$$ --> $$x = -15$$. We reject the solution because our condition is not satisfied (-15 is not within (-8,-3) interval.)

c) $$-3 \leq x < 4$$. $$+ (x+3)-(4-x) =+ (8+x)$$ --> $$x = 9$$. We reject the solution because our condition is not satisfied (-15 is not within (-3,4) interval.)

d) $$x \geq 4$$. $$+(x+3) + (4-x) = + (8+x)$$ --> $$x = -1$$. We reject the solution because our condition is not satisfied (-1 is not more than 4)

I am totally lost with this post and also with other modulus problems I looked up in Gmat club thank you very much for your help in advance!!!!!

I didn't understand how the sign for each expression was determined.
I'd appreciate any help.
Thanks!!
Intern
Joined: 10 Jul 2016
Posts: 30
Re: Math: Absolute value (Modulus)  [#permalink]

### Show Tags

26 Nov 2018, 15:07
Bunuel wrote:

When are we supposed to use the 3-step method? I mean, on which kind of problems?
Re: Math: Absolute value (Modulus) &nbs [#permalink] 26 Nov 2018, 15:07

Go to page   Previous    1   2   3   4   5   [ 91 posts ]

Display posts from previous: Sort by