For all numbers c and d, the operation @ is defined by c@d = c^2 - cd. If xy ≠ 0, then which of the following can be equal to zero?
I. x@y
II. (xy)@y
III. x@(x + y)
Choose the correct choice:	A) II	B) I and II	C) I and III	D) II and III	E) All of the above
c@d = c^2 - cd=c(c-d).... so c@d will be zero if c=d or c=0.. but a cannot be equal to 0.. as per Q, x and y can take any int value except 0...   now lets look at the choices..   when x=y, it will be 0... so ok...   when we put xy=y, it is possible when x=1 and y any integer... so ok again   when we put x=x+y.... only possibility when y=0 and it is given x and y cannot be 0....so not possible   only l and ll possible   answer: I and II
<result>B</result>
For all numbers c and d, the operation @ is defined by c@d = c^2 - cd. If xy ≠ 0, then which of the following can be equal to zero?
I. x@y
II. (xy)@y
III. x@(x + y)