the key is not to let the fractions confuse you. For a fraction to be positive, both the numerator and the denominator need to have the same sign - either both positive, or both negative. For example, 2/3 and -2/-3 will both be positive fractions, but -2/3 will not.Bnow wrote:If k does not equal 0, 1, or -1, is 1/k > 0?
1) 1/k-1> 0
2) 1/k+1>0
Having trouble reasoning through this one. The answer is A. But could someone explain this to me? Many thanks in advance!
thus, by asking "is 1/k>0, the question is really asking "is k>0?", since 1 is positive, k must be positive as well for the fraction to be positive.
Stat. (1): use the same logic: if 1/k-1>0 and the numerator is positive, then k-1 must be positive as well: k-1>0 means that k>1, which means that k is definitely positive (it's greater than 1!). The answer to the question stem is "yes", and stat. (1) is sufficient.
Stat. (2): the same thing, only now we know that k+1>0 --> k>-1, which allows both positive and negative values of k (k could b -0.5). thus, Stat. (2) allows both a yes and a no answer to the question stem, and is insufficient.
