I guess the question is about the number (2^n)(3^k)Originally Posted by scheng75
Otherwise it makes no sense
If this is the question, the answer is D because 42 has a factor 7 and the number (2^n)(3^k) doesn't.
This is a sample Miscellaneous Problems that Require Developing Problem-Solving Strategies of difficulty level 5 from the ETS website when I checked my results:
Which of the following CANNOT be a factor of 2n . 3k, where n and k are positive integers?
Please help me with a quick way of solving it!
the reasoning is as follows: when an integer A is a factor of another integer B? when there is another integer N such that: B = N*AOriginally Posted by scheng75
(2^n)(3^k) = N*A
every option but 42 satisfy this condition, for instance, for A = 6
(2^n)(3^k) = N*6 -> N = (2^(n-1)) * (3^(k-1))
but for A = 42 such N doesn't exist as A = 2*3*7:
N = [2^(n-1) * 3^(k-1)] / 7 -> N is not an integer
There are currently 1 users browsing this thread. (0 members and 1 guests)