Respostas

2014-05-25T19:01:31-03:00
1)y=x²-x-2
Xv= -b/2a
Xv= 1/2
Substituindo para encontrar Yv x=1/2
Y=1/2²-1/2-2= 1/4-1/2-2= -9/4
Δ= 1+8=9
x'= 2
x''= -1

2)y= x²-6x+9
Xv= 6/2=3
Subs...
y= 3²-6x3+9= 9-18+9= 0
Δ= 36-36=0
x'=x''= 3


3)y=x²-2x-3
Xv= 2/2=1
Subs...
y= 1²-2x1-3= 1-2-3= -4
Δ=4+12=16
x'= 3
x''= -1