If 4x−12>x+9, which o f the following must be true? A.

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If 4x−12>x+9, which o f the following must be true?

A. x>6
B. x<7
C. x>7
D. x>8
E. x<8

Answer: Option C
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by GMATinsight » Mon Oct 12, 2015 11:15 pm
GMATinsight wrote:If 4x−12>x+9, which o f the following must be true?

A. x>6
B. x<7
C. x>7
D. x>8
E. x<8

Answer: Option C
Solving 4x−12>x+9
i.e. 4x−x>12+9
i.e. 3x>21
i.e. x>7

Answer: option C

A. x>6 is Incorrect because as per this option x may be 6.5 whereas x must be Essentially Greater than 7
B. x<7 is Completely Incorrect because x must be Essentially Greater than 7
C. x>7 is CORRECT (Exactly what we have derived)
D. x>8 is Incorrect because as per this option x can NOT be 7.5 whereas x must be Essentially Greater than 7 which can be 7.5 as well
E. x<8 is Incorrect because as per this option x can NOT be 8.5 whereas x must be Essentially Greater than 7 and can be anything greater than 8 as well
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