chetan2u
If x is an integer, what is the value of |x-5|?
(1) (x-1)(x-9)=0
(2) (x-1)(2x-9)=0
Nice question, chetan2u!
Given: x is an integer Target question: What is the value of |x-5|? Statement 1: (x - 1)(x - 9) = 0From this, we can conclude that EITHER x = 1 OR x = 9
Aside: Many students will conclude that, since there are two possible values of x, statement 1 must be insufficient. These students, however, are answering the wrong target question. The target question isn't asking us to determine the value of x; it's asking us to determine the value of |x - 5| If x = 1, then
|x - 5| = |1 - 5| = |-4| = 4If x = 9, then
|x - 5| = |9 - 5| = |4| = 4Since the only two possible values of x yield the SAME answer to the target question, we can be certain that
|x - 5| = 4Statement 1 is SUFFICIENT
Statement 2: (x-1)(2x-9)=0From this, we can conclude that EITHER x = 1 OR x = 4.5
Since we are told that x is an
integer, x can't equal 4.5.
Since we can be certain that x = 1, the answer to the target question is
|x - 5| = |1 - 5| = |-4| = 4Statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent