Respostas

2013-11-30T17:32:31-02:00
A) Δ=7²-4x2x5
    Δ=49-40
    Δ=9
x= (-7 ± √ Δ )/2x2
x1=(-7+3)/4=-4/4=-1
x2=(-7-3)/4=-10/4=-5/2