Discussion
If x ≠ −1 and y ≠ ±1, then what is the value of 
?
*This question is included in Data Sufficiency Free Lesson Set, question #6
?
(1) x = 5
(2) y = 4
| (A) | if statement (1) ALONE is sufficient to answer the question but statement (2) alone is not sufficient; |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 03/26/2012 19:05
Why can't I simply plug in the value of y = 4 and arrive at the final answer? Both statements alone should be sufficient right?
Posted: 03/26/2012 19:41
AV, if we factor out x in the numerator, we can cancel (y-1) in both numerator / denominator. We can do this because the problem says y ≠ ±1. Otherwise (y-1) could have a value of 0 and we can't cancel. Left with an expression containing only the x variable, we don't need statement (2) to compute the value.