tissime wrote:

Thanks MacFauz and Bunuel. I understand your explanation and yes, OA is C.

However, can you tell me where I am wrong :

- Statement 1 is clearly not sufficient because z could be 5 or -5.

- Statement 2 is z = -|z|, you can rewrite the expression such as -z = IzI (wright?) if we multiply both side by -1. In that case the only possible value for z is 0 because the only possible solution is - 0 = I0I. So it is sufficient, no??

help me please.

Thanks

Yes, z = -|z| is the same as |z|=-z. But in this case z could be 0 or any negative number. For example, z=-2 --> |z|=|-2|=2 and -z=-(-2)=2 --> |z|=-z.

Absolute value properties:When \(x\leq{0}\) then \(|x|=-x\), or more generally when \(some \ expression\leq{0}\) then \(|some \ expression|\leq{-(some \ expression)}\). For example: \(|-5|=5=-(-5)\);

When \(x\geq{0}\) then \(|x|=x\), or more generally when \(some \ expression\geq{0}\) then \(|some \ expression|\leq{some \ expression}\). For example: \(|5|=5\).

For more check Absolute Value chapter of Math Book:

math-absolute-value-modulus-86462.htmlDS questions on absolute value to practice:

search.php?search_id=tag&tag_id=37PS questions on absolute value to practice:

search.php?search_id=tag&tag_id=58Tough absolute value and inequity questions with detailed solutions:

inequality-and-absolute-value-questions-from-my-collection-86939.htmlHope it helps.

_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis ; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) ; 12. Tricky questions from previous years.

COLLECTION OF QUESTIONS:

PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.

What are GMAT Club Tests?

25 extra-hard Quant Tests

GMAT Club Premium Membership - big benefits and savings