Resposta:

Explicação passo a passo:

y=x^2-5x+6

b^2-4ac

delta=(-5)^2-4.1.6

delta=25-24

delta=1

x=-b+-√delta/2a

x1=-(-5)+√1/2.1

x1=5+1/2

x1=6/2

x=3

x2=5-1/2

x2=4/2

x2=2

b)-x^2+4

b^2-4ac

delta=0^2-4(-1).4

delta=0+16

delta=16

x=-b+-√delta/2a

x1=0+√16/2

x1=0+4/2

x1=4/2

x1=2

x2=0-4/2

x2=-4/2

x=-2

c)x^2-4x+4

b^2-4ac

delta=(-4)^2-4.1.4

delta=16-16

delta=0

x=-b+-√delta/2a

x1=-(-4)+√0/2

x1=4+0/2

x1=4/2

x1=2

x2=-(-4)-√0/2

x2=4-0/2

x2=4/2

x2=2