actofman wrote:If ax + b = 0, is x > 0 ?
a) a + b > 0
b) a - b > 0
Given that ax + b = 0, if a=0, then b=0.
Looking at the statements, we can see that it is not possible that both a=0 and b=0.
Thus, we know that a≠0, allowing us to rephrase the question stem.
ax + b = 0
ax = -b
x = - (b/a).
Substituting -(b/a) = x into x > 0, we get:
-(b/a) > 0
b/a < 0.
Question stem rephrased: Do a and b have different signs?
Both statements are satisfied by a=10 and b=1.
In this case, a and b have the same sign.
Both statements are satisfied by a=10 and b=-1.
In this case, a and b have different signs.
Thus, the two statements combined are INSUFFICIENT.
The correct answer is
E.
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