HG10 wrote:Is |x - z| = |y - z|?
1. x = y
2. |x| - z = |y| - z
OA: A
Squaring is a nice trick, but you can always just create three non-abs formulas (only one of which need be validated):
a.) x - z = y - z
OR
b.) x - z = z - y
OR
c.) z - x = y - z
(1) x = y
Applying to (a), we get y - z = y - z, which is always true. SUFFICIENT
(2) |x| - z = |y| - z
z's cancel to leave |x| = |y|
x = y, from before we know that this validate's
AND
-x = y
a.) x = y = 0, does NOT always evaluate to true
b.) -z = z, is NEVER true
c.) z = -z, is NEVER true
Given part (2), the main statement works when x = y but does NOT work when x = -y.
INSUFFICIENT
A is the answer
