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Question Stats:
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If \(a\) and \(b\) are integers and \(ab=2\), is \(a=2\)? (1) \(b+3\) is not a prime number (2) \(a \gt b\)
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Re M2715
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16 Sep 2014, 01:27
Official Solution: Notice that we are not told that \(a\) and \(b\) are positive. There are the following possible integer pairs of \((a, b)\): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case. (1) \(b+3\) is not a prime number. This statement rules out 1st and 4th options. Not sufficient. (2) \(a \gt b\). This statement also rules out 1st and 4th options. Not sufficient. (1)+(2) Still two options are left: (1, 2) and (2, 1). Not sufficient. Answer: E
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Re: M2715
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08 Mar 2018, 15:40
There are the following possible integer pairs of (a,b)(a,b): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case.
(1) b+3b+3 is not a prime number. This statement rules out 1st and 4th options. Not sufficient.
Yes but, option one also rules out (1,2), as 3 + 2 = 1, which is a prime number. It rules out options 1, 2, and 4.



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Re: M2715
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27 Sep 2018, 06:00
deloitter wrote: There are the following possible integer pairs of (a,b)(a,b): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case.
(1) b+3b+3 is not a prime number. This statement rules out 1st and 4th options. Not sufficient.
Yes but, option one also rules out (1,2), as 3 + 2 = 1, which is a prime number. It rules out options 1, 2, and 4. That is not true. Number 1 is not prime



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Re: M2715
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28 Sep 2018, 02:58
I did not consider that the numbers could be both negatives. A mistake I need to avoid.
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Bunuel wrote: Official Solution:
Notice that we are not told that \(a\) and \(b\) are positive. There are the following possible integer pairs of \((a, b)\): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case. (1) \(b+3\) is not a prime number. This statement rules out 1st and 4th options. Not sufficient. (2) \(a \gt b\). This statement also rules out 1st and 4th options. Not sufficient. (1)+(2) Still two options are left: (1, 2) and (2, 1). Not sufficient.
Answer: E If \(a\) and \(b\) are integers and \(ab=2\), is \(a=2\)? Question here is whether A is 2 or not?? Considering situation (1) and from your explanation (1, 2) and (2, 1) can be values.. neither values has a=2, so its clear "a" is not 2, in that case i think its clear that a is not 2 hence, statement 1 is sufficient. though there are multiple values of a, but we have to answer whether a is 2 or not,, which is clear that it is not under statement 1. if m wrong pls help me.



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Re: M2715
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27 Oct 2018, 05:44
GMAT215 wrote: Bunuel wrote: Official Solution:
Notice that we are not told that \(a\) and \(b\) are positive. There are the following possible integer pairs of \((a, b)\): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case. (1) \(b+3\) is not a prime number. This statement rules out 1st and 4th options. Not sufficient. (2) \(a \gt b\). This statement also rules out 1st and 4th options. Not sufficient. (1)+(2) Still two options are left: (1, 2) and (2, 1). Not sufficient.
Answer: E If \(a\) and \(b\) are integers and \(ab=2\), is \(a=2\)? Question here is whether A is 2 or not?? Considering situation (1) and from your explanation (1, 2) and (2, 1) can be values.. neither values has a=2, so its clear "a" is not 2, in that case i think its clear that a is not 2 hence, statement 1 is sufficient. though there are multiple values of a, but we have to answer whether a is 2 or not,, which is clear that it is not under statement 1. if m wrong pls help me. Please reread.
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Re: M2715
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29 Oct 2018, 02:55
Bunuel wrote: GMAT215 wrote: Bunuel wrote: Official Solution:
Notice that we are not told that \(a\) and \(b\) are positive. There are the following possible integer pairs of \((a, b)\): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case. (1) \(b+3\) is not a prime number. This statement rules out 1st and 4th options. Not sufficient. (2) \(a \gt b\). This statement also rules out 1st and 4th options. Not sufficient. (1)+(2) Still two options are left: (1, 2) and (2, 1). Not sufficient.
Answer: E If \(a\) and \(b\) are integers and \(ab=2\), is \(a=2\)? Question here is whether A is 2 or not?? Considering situation (1) and from your explanation (1, 2) and (2, 1) can be values.. neither values has a=2, so its clear "a" is not 2, in that case i think its clear that a is not 2 hence, statement 1 is sufficient. though there are multiple values of a, but we have to answer whether a is 2 or not,, which is clear that it is not under statement 1. if m wrong pls help me. Please reread. pls reply..



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Re: M2715
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29 Oct 2018, 03:59
Bunuel wrote: GMAT215 wrote: Bunuel wrote: Official Solution:
Notice that we are not told that \(a\) and \(b\) are positive. There are the following possible integer pairs of \((a, b)\): (1, 2), (1, 2), (2, 1) and (2, 1). Basically, we are asked whether we have the third case. (1) \(b+3\) is not a prime number. This statement rules out 1st and 4th options. Not sufficient. (2) \(a \gt b\). This statement also rules out 1st and 4th options. Not sufficient. (1)+(2) Still two options are left: (1, 2) and (2, 1). Not sufficient.
Answer: E If \(a\) and \(b\) are integers and \(ab=2\), is \(a=2\)? Question here is whether A is 2 or not?? Considering situation (1) and from your explanation (1, 2) and (2, 1) can be values.. neither values has a=2, so its clear "a" is not 2, in that case i think its clear that a is not 2 hence, statement 1 is sufficient. though there are multiple values of a, but we have to answer whether a is 2 or not,, which is clear that it is not under statement 1. if m wrong pls help me. Please reread. I think you did not reread the solution. The solution clearly says that from statement (1) 1st and 4th options are NOT possible: This statement rules out 1st and 4th options. So, from (1) only (1, 2) and (2, 1) are possible, NOT (1, 2) and (2, 1).
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