alanforde800Maximus wrote:
If k is negative, which of the following must also be negative?
A) (-k)^2
B) (-1) k
C) 1 - k
D) k + 1
E) k - 1
NOTE: this is one of those questions that require us to check/test each answer choice. In these situations,
always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top.
For more on this strategy, see my article:
http://www.gmatprepnow.com/articles/han ... -questions So, beginning with E...
E) k - 1
If we think of the number line, we know that, since k is NEGATIVE, it lies to the LEFT of zero on the number line.
When we subtract 1, we move one unit (space) to the LEFT.
So, since k already lies to the left of zero on the number line, when we move one more space to the left, we will STILL BE left of zero on the number line
This means k-1 must be negative.
Answer: E
Cheers,
Brent
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Brent Hanneson – Creator of gmatprepnow.com
Before you spend another second preparing for the GMAT, check out my article series, Are you doing it wrong?.
You’ll learn what the GMAT actually tests, and why memorizing a ton of formulas actually makes you less effective.