if x + y/ z is equal to -2, is x positive?
(1) z is negative
(2) y is positive
(1) z is negative
(2) y is positive
TAKEAWAY:
if a problem asks about a certain quantity or variable(s), then you should ISOLATE that quantity or variable(s).
this problem asks a question about x. therefore, you should isolate x.
if you do this, you get x = -y - 2z.
therefore, you have the rephrase you want:is (-y - 2z) positive?
(1)
insufficient, because we don't know anything about -y (which could be any number at all, and which could definitely be big enough to overwhelm -2z).
(2)
insufficient, because we don't know anything about -2z (which could be any number at all, and which could definitely be big enough to overwhelm -y).
(together)
-y must be negative, but could be ANY negative number.
-2z must be positive, but could be ANY positive number.
the desired sum is therefore (arbitrary pos #) + (arbitrary neg #), which could work out to any number at all.
insufficient.
ans (e)
if a problem asks about a certain quantity or variable(s), then you should ISOLATE that quantity or variable(s).
this problem asks a question about x. therefore, you should isolate x.
if you do this, you get x = -y - 2z.
therefore, you have the rephrase you want:is (-y - 2z) positive?
(1)
insufficient, because we don't know anything about -y (which could be any number at all, and which could definitely be big enough to overwhelm -2z).
(2)
insufficient, because we don't know anything about -2z (which could be any number at all, and which could definitely be big enough to overwhelm -y).
(together)
-y must be negative, but could be ANY negative number.
-2z must be positive, but could be ANY positive number.
the desired sum is therefore (arbitrary pos #) + (arbitrary neg #), which could work out to any number at all.
insufficient.
ans (e)
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