Respostas

2014-05-12T18:15:53-03:00
5x - 2y    → x = -4 . y = -7

5.(-4) - 2.(-7)
-20 - 14
-34

2014-05-12T18:20:38-03:00
   5x - 2y para x = -4 e y = - 7
= 5 · (-4) - 2 · (-7)
= - 20 + 14
= -6