Respostas

2014-03-13T15:57:53-03:00
5x² + mx - 4 = 0 ; x = 2
5 · 2² + m · 2 - 4 = 0
5 · 4 + 2m - 4 = 0
20 + 2m - 4 = 0
2m = 0 - 20 + 4
2m = -16
m = -16/2
m = -8