What is the value of |z| ? (1) z = |z| (2) z^2 = 49

Question

What is the value of |z| ?

(1) z = |z|
(2) z^2 = 49

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GMATinsight · Answer

Question; |z| = ? Statement 1 : z = |z| i.e. z is NON-NEGATIVE but the value is unknown hence NOT SUFFICIENT Statement 2 : z^2 = 49 i.e. x = ±7 NOT SUFFICIENT Combining the statements z = +7 hence SUFFICIENT Answer: Option C GMATinsight We offer the highest Quality GMAT Tutoring and Admission Consulting | Book Demo 1st Video solutions based Modular On-Demand QUANT Course: All Concepts | 2000+Qns | 20+ Tests | Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub

YB10 · Answer

Won’t |z| be equal to 7? Hence answer is option B

Question; |z| = ?

Statement 1 : z = |z|

i.e. z is NON-NEGATIVE but the value is unknown hence
 NOT SUFFICIENT

Statement 2 : z^2 = 49 
i.e. x = ±7
 NOT SUFFICIENT

Combining the statements

z = +7 hence
 SUFFICIENT

Answer: Option C

GMATinsight

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guipjf · Answer

I agree with you. The question is asking what is the value of |z|. For me, |z| cannot be negative. I don't understand why answer C would be the correct one.

NewOldLearner · Answer

I think it’s bc -7^-7 (-7 x -7) would also = 49. You need the first statement to know that Z is a positive # (7) and not -7

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What is the value of |z| ? (1) z = |z| (2) z^2 = 49

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