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x(x–y)–z(x–y)=x(x–y)–z(x–y)= (A) x – y (B) x – z (C) (x – y)(x – z) (
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26 Feb 2021, 06:41
26 Feb 2021, 06:41
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93% (00:43) correct
6% (00:47) wrong based on 33 sessions
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x(x–y) – z(x–y) =
(A) x – y
(B) x – z
(C) (x – y)(x – z)
(D) (x – y)(x + z)
(E) (x – y)(z – x)
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
(A) x – y
(B) x – z
(C) (x – y)(x – z)
(D) (x – y)(x + z)
(E) (x – y)(z – x)
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
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Re: x(x–y)–z(x–y)=x(x–y)–z(x–y)= (A) x – y (B) x – z (C) (x – y)(x – z) (
[#permalink]
26 Feb 2021, 06:55
26 Feb 2021, 06:55
1
Carcass wrote:
x(x–y) – z(x–y) =
(A) x – y
(B) x – z
(C) (x – y)(x – z)
(D) (x – y)(x + z)
(E) (x – y)(z – x)
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
(A) x – y
(B) x – z
(C) (x – y)(x – z)
(D) (x – y)(x + z)
(E) (x – y)(z – x)
Kudos for the right answer and explanation
Question part of the project GRE Quantitative Reasoning Daily Challenge - (2021) EDITION
GRE - Math Book
APPROACH #1: Algebra
This is a matter of simplifying like terms.
Here's an example: 3x + 4x = (3 + 4)x = 7x
Likewise: x(x–y) – z(x–y) = (x - z)(x–y)
Answer: C
-----------------------------------------------------
APPROACH #2: Test values
We're looking for an expression that is EQUIVALENT to x(x – y) – z(x – y)
So, for any set of values for x, y and z, the correct answer must evaluate to have the same value as x(x – y) – z(x – y)
So, let's plug in some values for x, y and z
Let's try x = 3, y = 1 and z = 10
First plug those values into the GIVEN expression.
We get: x(x – y) – z(x – y) = 3(3 – 1) – 10(3 – 1)
= 3(2) – 10(2)
= 6 - 20
= -14
So, the correct answer choice will be the one that evaluates to -14 when we plug in x = 3, y = 1 and z = 10
(A) x – y = 3 - 1 = 2. We want -14. ELIMINATE A
(B) x – z = 3 - 10 = -7. We want -14. ELIMINATE B
(C) (x – y)(x – z) = (3 - 1)(3 - 10) = (2)(-7) = -14. GREAT! KEEP C
(D) (x – y)(x + z) = (3 - 1)(3 + 10) = (2)(13)= 26. We want -14. ELIMINATE D
(E) (x – y)(z – x) = (3 - 1)(10 - 3) = (2)(7)= 14. We want -14. ELIMINATE E
By the process of elimination, the correct answer is C
Cheers,
Brent
gmatclubot
Re: x(x–y)–z(x–y)=x(x–y)–z(x–y)= (A) x – y (B) x – z (C) (x – y)(x – z) ( [#permalink]
26 Feb 2021, 06:55
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