Solution :
Assume that . Then m must be an odd number and,
.
Hence and for some positive integers s and t.
Now,
and .
But is even and 3m is odd, a contradiction.
. Then m must be an odd number and,. Then m must be an odd number and,
.
and 
for some positive integers s and t. 
and 
.
is even and 3m is odd, a contradiction.