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QOTD#14 If w is a non-positive integer, which of the
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16 Nov 2016, 13:16
16 Nov 2016, 13:16
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If w is a non-positive integer, which of the following must be positive?
Indicate all possible value
A. \(−3w\)
B. \(2w + 10\)
C. \(w^4\)
D. \(w^0\)
E. \(−w + 0.5\)
Indicate all possible value
A. \(−3w\)
B. \(2w + 10\)
C. \(w^4\)
D. \(w^0\)
E. \(−w + 0.5\)
Drill 4
Question: 7
Page: 294
Question: 7
Page: 294
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Re: QOTD#14 If w is a non-positive integer, which of the
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02 Jan 2017, 17:08
02 Jan 2017, 17:08
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sandy wrote:
If w is a non-positive integer, which of the following must be positive?
Indicate all possible values.
A. −3w
B. 2w + 10
C. w^4
D. w^0
E. −w + 0.5
Indicate all possible values.
A. −3w
B. 2w + 10
C. w^4
D. w^0
E. −w + 0.5
Drill 4
Question: 7
Page: 294
Question: 7
Page: 294
Show: :: OA
D and E
There's a slight problem with answer choice D.
If we let w = 0 (a non-positive integer), then w^0 = 0^0 and 0^0 is not defined (see page 141 of the Official Guide to the GRE - 3rd edition)
If 0^0 is not defined, we cannot say that 0^0 is positive.
So, there's only answer correct answer: E
Cheers,
Brent
General Discussion
Re: QOTD#14 If w is a non-positive integer, which of the
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16 Nov 2016, 13:23
16 Nov 2016, 13:23
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Expert Reply
Explanation
Remember to Plug In multiple times for must be questions. First, use an easy number, such as −1, and try it in each choice. All of the answers are positive, so don’t eliminate anything. Can we eliminate anything by making w smaller? A number such as −10 will allow us to eliminate choice (B), but everything else is still positive. But can w = 0? Non-positive just means the number can’t be positive—it doesn’t mean it can’t be zero.
Hence options D and E are correct.
Note: Option B is negative if w is large enough.
Remember to Plug In multiple times for must be questions. First, use an easy number, such as −1, and try it in each choice. All of the answers are positive, so don’t eliminate anything. Can we eliminate anything by making w smaller? A number such as −10 will allow us to eliminate choice (B), but everything else is still positive. But can w = 0? Non-positive just means the number can’t be positive—it doesn’t mean it can’t be zero.
| w = -1 | w = 0 | |
| 3w | 3 | 0 |
| 2w+10 | 8 | 10 |
| w^4 | 1 | 0 |
| w^0 | 1 | 1 |
| -w+0.5 | 1.5 | 0.5 |
Hence options D and E are correct.
Note: Option B is negative if w is large enough.
