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knight247
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Is A>O?
(1)A³-A< 0
(2)1-A²> 0
This problem is from the Manhattan Guides. Just a real quick clarification that I need. I've figured the answer is C. But I did it in a much simpler way as compared to the complicated explanation given in the book.
From (1)
A(A²-1)<0
Meaning either A>0 and (A²-1)<0
Or A<0 and (A²-1)>0
This gives us conflicting values of A and hence INSUFFICIENT. Is my reasoning sufficient? Do I need to do any further testing?
From (2)
A²<1
|A|<1
-1<A<1
Again giving us conflicting values hence INSUFFICIENT.
Combining both
(2) Can be written as -A²+1> 0
Multiplying by -1 we get (A²-1)<0
Using this piece of information in statement 1, Since (A²-1)<0 then A has to be positive making A>0
Hence C. I would appreciate a clarification on the bold highlighted portion. Thanks
(1)A³-A< 0
(2)1-A²> 0
This problem is from the Manhattan Guides. Just a real quick clarification that I need. I've figured the answer is C. But I did it in a much simpler way as compared to the complicated explanation given in the book.
From (1)
A(A²-1)<0
Meaning either A>0 and (A²-1)<0
Or A<0 and (A²-1)>0
This gives us conflicting values of A and hence INSUFFICIENT. Is my reasoning sufficient? Do I need to do any further testing?
From (2)
A²<1
|A|<1
-1<A<1
Again giving us conflicting values hence INSUFFICIENT.
Combining both
(2) Can be written as -A²+1> 0
Multiplying by -1 we get (A²-1)<0
Using this piece of information in statement 1, Since (A²-1)<0 then A has to be positive making A>0
Hence C. I would appreciate a clarification on the bold highlighted portion. Thanks
