Question

Điền vào ô trống:

x	5	–18		–25
y	–7	10	–10
x . y			–180	–1000

Answer 1

x	5	–18	18	–25
y	–7	10	–10	40
x . y	-35	-180	–180	–1000

+ x = 5, y = –7 thì x . y = 5. ( –7) = – (5 . 7) = –35.

+ x = –18, y = 10 thì x . y = (–18) . 10 = – (18 . 10) = –180.

+ y = –10 ; x.y = x . (–10) = – (x.10) = – 180, do đó x . 10 = 180 nên x = 18.

+ x = –25; x.y = (–25).y = –(25.y) = –1000, do đó 25.y = 1000 nên y = 40.