If |x - 3| 1 then which of the following must be true?

Question

If  |x - 3| > 1  then which of the following must be true?

I.  |x| > 4 
II.  x^2 > 16 
III.  x > 4

A. I only
B. II only
C. III only
D. I, II and III
E. None

Bunuel · Accepted Answer

SOLUTION: |x - 3| > 1 means that: x - 3 > 1 --> x > 4 -(x - 3) > 1 --> x < 2 So, we are given that x < 2 or x > 4 . I. |x| > 4 . Not necessarily true. Consider x = 0. II. x^2 > 16 . Not necessarily true. Consider x = 0. III. x > 4 . Not necessarily true. Consider x = 0. Answer: E. To understand the underline concept better practice other Trickiest Inequality Questions Type: Confusing Ranges .

MayankSingh · Answer

Refer attached Image.

Ans. E

RJ7X0DefiningMyX · Answer

Easy. What |x−3|>1 depicts is that x is at a distance of more than 1 from 3 on the number line, and thus, x>4 OR x<2

For x=1, |x−3|>1, |1-3| = |-2| = 2 and 2>1 and hence, x=1 satisfies the inequality

Now quickly looking at all the options, x=1 does not fit in any of the three, and hence <1 min., you can arrive at your answer, i.e. (E) None

Kinshook · Answer

If |x−3|>1
 then which of the following must be true?

I. |x|>4
II. x^2>16
III. x>4

A. I only
B. II only
C. III only
D. I, II and III
E. None

|x-3|>1
x>4 or x<2

I. |x|>4
Take for example x =1 => |x-3| = |1-3| = 2>1 satisfies the equation. But |1| is not >4. NOT NECESSARILY TRUE.
II. x^2>16
Take for example x =1 => |x-3| = |1-3| = 2>1 satisfies the equation. But 1^2 is not >16. NOT NECESSARILY TRUE.
III. x>4
Take for example x =1 => |x-3| = |1-3| = 2>1 satisfies the equation. But 1 is not > 4. NOT NECESSARILY TRUE.

IMO E

Lampard42 · Answer

Two ways to solve :

Method 1) Find a counter example (easiest), X=-1 will satisfy the stem

I. |x|>4 - since x = -1 will satisfy this is not true
II. x^2>16 - since x = -1 will satisfy this is not true
III. x>4 - since x = -1 will satisfy this is not true

IMO E None

Method 2: solve using modulus properties to arrive at X cannot lie from 2 to 4. it can take any other value.

GMATinsight · Answer

If |x−3|>1 then which of the following must be true?

I. |x|>4
II. x^2>16
III. x>4

|x−3|>1

I.e. x > 4 or x < 2

So none of them is essentially true as x may be 1 which negates all

Posted from my mobile device

Sayon · Answer

|x – 3| > 1 will have two cases:
Case 1: x – 3 > 1 => x > 4
Case 2: -x + 3 > 1 => -x > -2 => x < 2

So we have x such that x<2 and x>4. Thus, x can take values such as -5, -1, -0.5, 0, 0.5, 1, 5, 10

I. |x|>4
We can have x = 0.5. Therefore, this need not be true.

II. x^2>16
Again we can have x = 0.5, where x^2 = 0.25. Therefore, this need not be true.

III. x>4
We can have x = -1. Therefore, this need not be true.

Answer E.

freedom128 · Answer

If |x−3|>1 then which of the following must be true?
I. |x|>4
II. x^2>16
III. x>4

Given that |x−3|>1, it follows that x<2 or x>4. Possible values of x include 0,1,5,...

I. |x|>4
Given that |x|>4, it follows that x<-4 or x>4.
For every value that |x−3|>1 can take (e.g. x=0,1,5), must it be true that x<-4 or x>4 ? Nope.
Although x=5 fits well within |x|>4, both x=0 and x=1 never do.
Statement I is not necessarily true

II. x^2>16
Given that x^2>16, it follows that (x-4)(x+4)>0 and then x<-4 or x>4.
For every value that |x−3|>1 can take (e.g. x=0,1,5), must it be true that x<-4 or x>4 ? Nope.
Although x=5 fits well within x^2>16, both x=0 and x=1 never do.
Statement II is not necessarily true

III. x>4
For every value that |x−3|>1 can take (e.g. x=0,1,5), must it be true that x>4 ? Obviously not. Both x=0 and x=1 never satisfy x>4.
Statement III is not necessarily true

Answer is (E) None.

vedha0 · Answer

if this question was COULD BE TRUE one, then answer would have beeen all I,II,III

nice question with nuanced wording. one must be careful with MUST-BE-TRUE and COULD-BE-TRUE questions!

Prince1890Sharma · Answer

Hello  Bunuel ,

I have a query for every must be true kinda questions,
Do we have to look for an answer choice, that should contain all the values of variable mentioned like in this question x>4 and x<2. So an answer choice should contain both of them?
Or if it is only a subset of this range of x mentioned, that also can be an answer?

Bunuel · Answer

We are given that x < 2 or x > 4:

------------ 2------------4 ------------

So, x is somehere in the green region.

The question asks which of the statements MUST be true about x. The statement to be true must be true for all possible values of x. For instance, |x| > 4 is not necessarily true about x, because x can be 0, and in this case |x| > 4 won't be true. Similarly, we can see that none of the statements must be true about x.

bumpbot · Answer

Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

If |x - 3| > 1 then which of the following must be true?

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions