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15 Jul 2015, 03:05
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
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Question Stats:
84% (01:50) correct
16%
(02:25)
wrong
based on 193
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If x # y = 3x^2 – y and x @ y = x + 2y, which of the following is equal to 2x # (2x @ y)?
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
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15 Jul 2015, 04:20
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Bunuel
If x # y = 3x^2 – y and x @ y = x + 2y, which of the following is equal to 2x # (2x @ y)?
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
Given: x # y = 3x^2 – y and x @ y = x + 2y
2x@y = 2x+2y ----> 2x#(2x+2y) ----> 3 (2x)^2- (2x+2y) ---> 12x^2-2x-2y. Thus E is the correct answer.
Updated on: 15 Jul 2015, 05:37
Originally posted by GMATinsight on 15 Jul 2015, 05:26.
Last edited by GMATinsight on 15 Jul 2015, 05:37, edited 2 times in total.
Last edited by GMATinsight on 15 Jul 2015, 05:37, edited 2 times in total.
Kudos
Bookmarks
Bunuel
If x # y = 3x^2 – y and x @ y = x + 2y, which of the following is equal to 2x # (2x @ y)?
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
A. 2x^2 + 8xy + 4y^2
B. -x^2 + 8x – 4y
C. 10x^2 – 8 – 4y
D. 8x^2 – 4y^2
E. 12x^2 – 2x – 2y
Kudos for a correct solution.
Given : x # y = 3x^2 – y and x @ y = x + 2y,
Such questions can very well be solved with some substitution of value
Let, @x=1 and y=1
2x @ y = 2 1 = 2 + 2*1 = 4
Question stem has value, 2x # (2x @ y) = 2*1 # (4) = 2 # 4 = 3*2^2 - 4 = 12 - 4 = 8
Options @x=1 and y=1
A. 2x^2 + 8xy + 4y^2 = 2 + 8 + 4 = 14 i.e. not equal to 8 INCORRECT OPTION
B. -x^2 + 8x – 4y = -1 + 8 - 4 = 3 i.e. not equal to 8 INCORRECT OPTION
C. 10x^2 – 8 – 4y = 10 - 8 - 4 = -2 i.e. not equal to 8 INCORRECT OPTION
D. 8x^2 – 4y^2 = 8 - 4 = 4 i.e. not equal to 8 INCORRECT OPTION
E. 12x^2 – 2x – 2y = 12 - 2 - 2 = 8 CORRECT OPTION
Answer: Option E
