Here x and y are two numbers whose sum is 1 and product is -2. A useful HSC-level trick is to think of them as roots of the quadratic equation t² - (1)t + (-2) = 0. After factoring or solving that quadratic, we get the two possible numbers. Since the question asks for ordered pairs, the order matters: if the two numbers are different, both (first, second) and (second, first) are valid. Checking the selected pair(s), each one has sum 1 and product -2. Therefore the correct answer choices are (2, -1), (-1, 2).