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# QOTD#15 If |x^2y| = |(–w)z|, then which of the following

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QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  20 Nov 2016, 10:03
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Question Stats:

25% (01:40) correct 75% (01:22) wrong based on 4 sessions
If $$|x^2y| = |(-w)z|$$, then which of the following could be true?

Indicate all possible values.

A. $$x^2 = wz$$
B. $$|x^2y| = |(-w)z|$$
C. $$-(wz) = wz$$
D. $$|-x^2| = |(-w)z|$$
E. $$-w = z$$
F. $$x^2 = -|y|$$

Drill 4
Question: 9
Page: 294

[Reveal] Spoiler: OA
A, C, D, and E
[Reveal] Spoiler: OA

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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1652 [0], given: 396

Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  20 Nov 2016, 10:07
Expert's post
Explanation

The best way to approach a could be question is to consider many different kinds of numbers to plug in that could work in the problem. We will have to plug in a few times here, so let’s start with easy numbers. For instance, let’s try making every variable in the problem equal to 1.

Immediately, choices (A) and (D) work. If we made w = 1 and z = −1, then choice (E) works as well. Try plugging in 0 for either w or z and choice (C) can also work. In the end, choices (B) and (F) are always going to have a positive value on the left side of the equation and a negative value on the right, and therefore will not be correct. An absolute value is always positive, so it can never equal something negative.

Hence option A, C, D, and E are correct.
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Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  26 Aug 2017, 09:59
Actually if you plug in 0 for all variables all of the answers are correct. Am I missing something here?
GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1652 [0], given: 396

Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  27 Aug 2017, 03:19
Expert's post
jezzsk8 wrote:
Actually if you plug in 0 for all variables all of the answers are correct. Am I missing something here?

We tend to avoid plugging 0 in questions unless it is very clear that 0 is one of the possible solutions.
We absolutely avoid plugging 0 on both sides of an '=' sign.

This is because when you multiply both sides of any expression with zero the equality will always hold.

Say 300 = 500 is incorrect! But $$300 \times 0 = 500 \times 0$$ is correct!

So even in this question if you plug 0 make sure it doesnot have an impact on both sides of the equation
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Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  28 Aug 2017, 07:09
Alright, got it. Thanks. BTW how come option B isn't an answer when it's the exact same expression as in the question?
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Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following [#permalink]  15 Jun 2018, 15:03
I agree, why is B is not the right answer, since it is the same option as the question?
Re: QOTD#15 If |x^2y| = |(–w)z|, then which of the following   [#permalink] 15 Jun 2018, 15:03
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