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14 May 2012, 16:52
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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%
(low)
Question Stats:
76% (00:55) correct
24%
(00:43)
wrong
based on 199
sessions
History
Date
Time
Result
Not Attempted Yet
14 May 2012, 19:37
Kudos
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1)x2 - 5x + 4 = 0
x^2 - 4x -x +4=0
(x-4 ) (x-1) = 0
x= 4 , x=1
Not sufficient
2) x is not prime , Not sufficient
1&2) Both x= 4 and x=1 are not prime.
So , insufficient.
Therefore , E is the answer.
x^2 - 4x -x +4=0
(x-4 ) (x-1) = 0
x= 4 , x=1
Not sufficient
2) x is not prime , Not sufficient
1&2) Both x= 4 and x=1 are not prime.
So , insufficient.
Therefore , E is the answer.
17 Feb 2015, 07:24
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info2scs
ALTERNATE METHOD:
Question: Value of x = ?
Statement 1: x^2 - 5x + 4 = 0
Points to Know...
1) It's a Quadratic equation which has two roots which represent values of x
2) Compare the equation with ax^2 + bx + c = 0 i.e. a=1, b=-5, c=4
if b^2 - 4ac =0 Roots are equal
if b^2 - 4ac >0 Roots are unequal and real
if b^2 - 4ac <0 Roots are unequal and Imaginary which is beyond purview of GMAT
here, b^2 - 4ac = (-5)^2 - (4x1x4) = 25-16 = 9 i.e. roots (values of x) are unequal
Inconsistent values of x therefore NOT SUFFICIENT
Statement 2: x is not prime
There are infinite numbers that are not prime
i.e. Inconsistent values of x therefore NOT SUFFICIENT
Combining the two statements
x^2 - 5x + 4 = 0
i.e. x^2 - 4x - x + 4 = 0
i.e. x(x-4) - 1(x-4) = 0
i.e. (x-4)(x-1) = 0
i.e. x = 4 or 1
Second statement says that x is not prime but 1 and 4 are both non-prime numbers
therefore x can still be either 1 or 4 after combining the information of both statements
therefore, NOT SUFFICIENT
Answer: Option
