If two of the four expressions x+y, x+5y, x-y, and 5x-y are chosen at random, what is the probability Q that their product will be of the form of x^2-(by)^2, where b is an integer?	Choose the correct option:	A) Q=1/2	B) Q=1/3	C) Q=1/4	D) Q=1/5	E) Q=1/6
Only (X+y)(x-y) pair will give the form x^2-(by)^2   The probability of selecting these two pairs are 1/4 * 1/3 = 1/12, assuming x+y is picked first, then x-y, but x-y can be picked first followed by x+y. So the probability Q= 1/12 * 2 = 1/6   Ans Q=1/6
<result>E</result>
If two of the four expressions x+y, x+5y, x-y, and 5x-y are chosen at random, what is the probability Q that their product will be of the form of x^2-(by)^2, where b is an integer?