Prove that if x and y are both odd positive integers, then x2 + y2 is even but not divisible by 4.
Show that the square of any positive integer cannot be of the form 6m + 2 or 6m + 5 for any integer m.
Show that the square of any positive integer cannot be of the form 5q + 2 or 5q + 3 for any integer q.
Show that cube of any positive integer is of the form 4m, 4m + 1 or 4m + 3, for some integer m.
Show that the square of any positive integer is either of the form 4q or 4q + 1 for some integer q.
Show that the square of an odd positive integer is of the form 8m + 1, for some whole number m.