If x and y are positive integers, and 4x^2=2y, then which of the following must be a multiple of 9?
I. x^2
II. y^2
III. xy	Choices.
A) I only B) II only C) III only D) I and II only E) I, II and III
4x^2 = 3y   since x,y are positive integers, x^2 = x*x is divisible by 3 -&gt; x is divisible by 3 and y is divisible by x^2   -&gt; x^2 and y is divisible by 9 -&gt; y^2 is divisible by 9   (1),(2), and (3) must be true   Answer is II only
<result>B</result>
If x and y are positive integers, and 4x^2=2y, then which of the following must be a multiple of 9?
I. x^2
II. y^2
III. xy