st(1) n must be odd; a^n OR (n-1) power should bring even power at any time, hence will make the perfect square. Sufficient;
st(2) results in y=5^(n-1); if n is odd then y is a perfect square, if n is even then y is not a perfect square. Not Sufficient.
IOM A
yellowho wrote:Can someone one break down 2. Just wondering whether there's an alternative method:
