Question 46: Find the integers x, y such that: xy = 5 and x – y = −4

A. x = -1 and y = 5, or x = −5 and y = 1

B. x = 1 and y = -5, or x = 5 and y = −1

C. x = -1 and y = -5, or x = 5 and y = 1

D. x = 1 and y = 5, or x = −5 and y = −1

xy = 5 = 5.1 = (−5).(−1).

So x = 5 and y = 1 (doesn’t satisfy x-y =− 4)

x = 1 and y = 5 ⇒ x − y = 1 – 5 = −4 (receive)

x = −5 and y = −1 ⇒ x − y = −5 – (−1) = −4 (get)

x = 1 and y = −5 (does not satisfy x − y = −4)

So x = 1 and y = 5, or x = −5 and y = −1

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