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Math Expert V
Joined: 02 Sep 2009
Posts: 60460
What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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Difficulty:   5% (low)

Question Stats: 95% (00:45) correct 5% (01:00) wrong based on 883 sessions

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What is the value of $$x^2yz − xyz^2$$, if x = − 2, y = 1, and z = 3?

(A) 20
(B) 24
(C) 30
(D) 32
(E) 48

_________________
Intern  B
Joined: 12 Jun 2015
Posts: 37
Schools: Sloan '19
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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Given : x = − 2, y = 1, and z = 3

x^2yz − xyz^2,
= xyz (x- z)
= (-2)(1)(3) [ (-2) - 3]
= (-6)*(-5)
= 30
Hence C.
Manager  B
Joined: 07 May 2015
Posts: 174
Location: India
GMAT 1: 660 Q48 V31
GPA: 3
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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4*1*3 -(- 2*1*9)
=12+18 = 30

Ans: C
Intern  Joined: 23 Apr 2016
Posts: 6
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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can someone please explain this a bit more? I just substituted and definitely didnt come close
Math Expert V
Joined: 02 Aug 2009
Posts: 8341
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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2
JSS16 wrote:
can someone please explain this a bit more? I just substituted and definitely didnt come close

Hi,

the Q is --- What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3? ..

$$x^2yz − xyz^2 = xyz(x-z) = (-2)*1*3*(-2-3) = (-2)*1*3*(-5) = 1*3*10=30$$...
C
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Status: QA & VA Forum Moderator
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Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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1
Bunuel wrote:
What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?

(A) 20
(B) 24
(C) 30
(D) 32
(E) 48

$$x^2$$$$yz$$ = $$-2^2$$$$(1*3)$$ => 12

$$xy$$$$z^2$$ = $$(-2*1)3^2$$ => -18

So, $$x^2$$$$yz$$ − $$xy$$$$z^2$$ = 12 - (-18) => 30

Hence answer will be (C) 30
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Intern  Joined: 18 Aug 2016
Posts: 1
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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Bunuel wrote:
What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?

(A) 20
(B) 24
(C) 30
(D) 32
(E) 48

The confusion created in this question is that they could have included brackets.

ie (x^2)yz - xyz^2..

Else people like me will take x^(2yz)-xyz^2.

Is there any rule for this? Please tell me if so.
Math Expert V
Joined: 02 Sep 2009
Posts: 60460
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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1
wolf020287 wrote:
Bunuel wrote:
What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?

(A) 20
(B) 24
(C) 30
(D) 32
(E) 48

The confusion created in this question is that they could have included brackets.

ie (x^2)yz - xyz^2..

Else people like me will take x^(2yz)-xyz^2.

Is there any rule for this? Please tell me if so.

x^2yz mathematically can only mean x^2*y*z. If it were 2 to the power of 2yz, then it would be written as x^(2yz). Still edited the original post to avoid confusion.
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Board of Directors D
Status: QA & VA Forum Moderator
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Posts: 4850
Location: India
GPA: 3.5
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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Bunuel wrote:
What is the value of $$x^2yz − xyz^2$$, if x = − 2, y = 1, and z = 3?

(A) 20
(B) 24
(C) 30
(D) 32
(E) 48

$$(-2)^2*1*3 − (-2)*1*3^2$$

=4*1*3 - ( -2)*1*9
= 12 - (-18)
= 30

Hence answer will be (C) 30

_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
Manager  S
Status: On a 600-long battle
Joined: 22 Apr 2016
Posts: 136
Location: Hungary
Schools: Erasmus '19
GMAT 1: 410 Q18 V27 GMAT 2: 490 Q35 V23
What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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For this question, you must to remember that you need to factor common terms out, then it's just plug and play, and obviously, avoid silly mistakes (I'm talking directly to myself here!) and go bit by bit, just like Jack the Ripper:

$${ x }^{ 2 }yz-xy{ z }^{ 2 }=\\ xyz\left( x-y \right) =\\ \left[ \left( -2 \right) \left( 1 \right) \left( 3 \right) \right] \left( -2-3 \right) =\\ \left( -6 \right) \left( -5 \right) =\\ 30$$
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Manager  G
Joined: 06 Sep 2018
Posts: 170
Location: Pakistan
Concentration: Finance, Operations
GPA: 2.87
WE: Engineering (Other)
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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1
xyz(x-z)
(-2)(1)(3)(-2-3)
(-6)(-5)
30
Intern  S
Joined: 22 Jun 2018
Posts: 31
Location: India
GMAT 1: 670 Q49 V34
GRE 1: Q170 V160
GPA: 3.82
Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  [#permalink]

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1
=> x= -2, y = 1, z = 3,

=> xyz[x-z]

=> (-2)(1)(3)(-2-3)

=> (-6)(-5)

=> 30 Re: What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?   [#permalink] 14 May 2019, 06:06
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# What is the value of x^2yz − xyz^2, if x = − 2, y = 1, and z = 3?  