If xy 0, is x > y? (1) 4x = 3y (2) |y - x| = x - y

This is a good question, simple with a small trap

|y - x| = x - y

y - x = x - y
2x = 2y
x=y so answer is no

-y + x = x-y
0=0
answer is no

sufficient

st 1) y=1, x=3/4 - false
y=-1, x=-3/4 - true
Not sufficient
st 2)
|y-x| =x-y--> x>y
Sufficient
coz |-x| = -(-x) = x -- basically a negative numbers should be negated again to get the result for absolute value
all the cases as cay that x>y but fails when x=y

combining we can answer the question

C

<didnt consider x=y option, so answered as B >

B alone is not sufficient as we dont know whether x=y?

So A gives information that x is not = y.

So Final ans is C
This was nice question...even I would have done the same mistake in the exam..Its really important to think of all the possibilities on the G day.

Given: \(xy\neq0\). Question: is \(x>y\) true?

(1) \(4x = 3y\) --> if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\).

(2) \(|y-x|=x-y\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) --> so \(x-y\geq0\) --> then \(|y-x|=-(y-x)\), and we'll get \(-(y-x)=x-y\) --> \(0=0\), which is true. This means that equation \(|y-x|=x-y\) holds true when \(x-y\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient.

(1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient.

Answer: C.

Hope it helps.

Dear Bunuel:

I am a bit confused with this problem. I don't have a problem to understand the first statement, but I do have a problem trying to understand the second one..

I saw a user on this thread was solving the second statement as this:

2. |y - x| = x - y

y - x = x - y
2x = 2y
x=y

-y + x = x-y
0=0

Isn't his way of solving the correct way to solve this kind of problems? I have seen some other exercises and they always negate the LHS that has the absolute value on it regarding of the inequality symbol or equality. I would like to learn why we are not doing this on this problem.

If I am wrong, would you be so kind to revamp the way of solving statement 2, I already read the way you solved it, but it was not 100% clear for me.

Thanks in advance.

There can be many correct ways to solve a questions.

Try this one: (2) says that \(|y-x|=-(y-x)\). We know that \(|x|=-x\), when \(x\leq{0}\), thus \(y-x\leq{0}\).

If xy ≠ 0, is x > y?

(1) 4x = 3y

(2) |y - x| = x - y

Consider (1)
4x=3y ; x=3/-3 and y =4/-4 satisfy this condition. so x can be > y or x can be <y.
insufficient

Consider (2)

|y - x| = x - y
x= 4 y =3 satisfy this , and x>y
x= 3 y=3 satisfy this but x =y
x= 3 and y = 4 doesnt satisfy
x=-3 and y =-4 satisfy this and x >y
hence insufficient

combining 1 and 2 the only option that satisfy 1 and 2 is x=-3 and y=-4 and hence x>y

Therefore C is the answer.

Hello Bunuel,

Thank you for your answer. Although , as per mod property, isn't it the case that |x| = x when x>=0 and -x when x<0 ? I would like to know why you are considering |x| = -x when x<=0, because this is where the answer is really hinged on.

Thanks!

|0| = 0 = -0, so you can include = sign in either of the cases: |x| = -x, when x<=0 and |x| = x, when x >= 0.

For (1), isn't it the opposite? when both +ve x<y, when both -ve x>y.

Yes but that doesn't change the answer anyway.

Kudos for the explanation. Am having trouble with absolute value and inequalities. How can I improve????

9. Inequalities

• Theory
  Inequalities Made Easy!
  Inequalities: Tips and hints
  Arithmetic with Inequalities
  Wavy Line Method Application - Complex Algebraic Inequalities
  Solving Quadratic Inequalities: Graphic Approach
  Inequalities - Quadratic Inequalities
  Graphic approach to problems with inequalities
  Inequalities trick
  INEQUATIONS(Inequalities) Part 1
  INEQUATIONS(Inequalities) Part 2
  
  • Questions
    Inequality and absolute value questions from my collection
    DS Questions
    PS Questions
  
  

  10. Absolute Value

  
  
  • Theory
    Math: Absolute value (Modulus)
    Absolute Value: Tips and hints
    Properties of Absolute Values on the GMAT
    Absolute modulus : A better understanding
    GMAT Question Patterns: Abolute Value
    The Reason Behind Absolute Value Questions on the GMAT
    
    • Questions
      Inequality and absolute value questions from my collection
      The E-GMAT Question Series on ABSOLUTE VALUE
      DS Questions
      PS Questions

For more check Ultimate GMAT Quantitative Megathread

Hope it helps.

silly Mistake and end up with

(1) 4x = 3y: insufic
x=3/4*y
x,y>0: then x<y…y=1, x=3/4(1)=3/4<1
x,y<0: then x>y…y=-2, x=3/4(-2)=-1.5>-2

(2) |y - x| = x - y: insufic
|y-x|≥0…x-y≥0…x≥y; x=y or x>y

(1/2) sufic
since x=3/4y then x≠y, thus x>y

Ans (C)

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