is x a negative number ?
1. 9x> 10x
2.x+3 is positive
plz explain the answer
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pradeepkaushal9518
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neoreaves
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IMO A
1) 9x > 10x
x >10/9x
x > 1.1x
if x > 0 then divide both sides by x 1 > 1.1 which is not true
if x <0 then to divide both sides we have to flip the inequality 1< 1.1 which is true
Thus sufficient
2) x = -2 satisfies this so does x = 100 so Insufficient
Ans: A
1) 9x > 10x
x >10/9x
x > 1.1x
if x > 0 then divide both sides by x 1 > 1.1 which is not true
if x <0 then to divide both sides we have to flip the inequality 1< 1.1 which is true
Thus sufficient
2) x = -2 satisfies this so does x = 100 so Insufficient
Ans: A
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Testluv
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We can also just use reasoning/picking numbers.
(1) 9x>10x
If x were positive, say positive 2, would the inequality be satisfied? That is, is 9(2) > 10(2)? Clearly not. Thus, x cannot be positive.
If x were zero, would the inequality be satisifed? That is, is 9(0) > 10(0)? Clearly not. Thus, x cannot be zero.
Thus, x must be negative.
As neoreaves points out, the information in (2) allows for x to be either positive or negative. Thus, the answer to the question "is x negative?" is "we don't know for sure".
(1) is sufficient by itself but (2) is not. Choose A.
(1) 9x>10x
If x were positive, say positive 2, would the inequality be satisfied? That is, is 9(2) > 10(2)? Clearly not. Thus, x cannot be positive.
If x were zero, would the inequality be satisifed? That is, is 9(0) > 10(0)? Clearly not. Thus, x cannot be zero.
Thus, x must be negative.
As neoreaves points out, the information in (2) allows for x to be either positive or negative. Thus, the answer to the question "is x negative?" is "we don't know for sure".
(1) is sufficient by itself but (2) is not. Choose A.
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Scott@TargetTestPrep
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We need to determine whether x is a negative number.pradeepkaushal9518 wrote:is x a negative number ?
1. 9x> 10x
2.x+3 is positive
Statement One Alone:
9x > 10x
Simplifying we have:
9x - 9x > 10x - 9x
0 > x
Since 0 is greater than x, x is less than 0. In other words, x must be negative.
Statement one alone is sufficient to answer the question.
Statement Two Alone:
x + 3 is positive.
From statement two we see that x itself could be either positive or negative.
If x is positive
Let x = 1:
1 + 3 = 4, which is positive.
If x is negative
Let x = -1:
-1 + 3 = 2, which is also positive.
Statement two alone is not sufficient to answer the question.
Answer: A
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