x²-3x+5<0
x²-3x+5=0
D=b²-4ac=9-20=-11 => nu are soluții în R => Ø
x²-5x+4>0
x²-5x+4=0
D=b²-4ac=25-16=9
x¹=5+3/2=8/2=4
x²=5-3/2=2/2=1
S: x€(infinit, 1) U (4, -infinit)
x | infinit 1 4 -infinit
____________________
ec|++++++++0-----0++++++++
x²-6x+9>=0
x²-6x+9=0
D=b²-4ac=36-36=0
x¹=x²=6/2=3
x | infinit 3 -infinit
____________________
ec|++++++++++0++++++++++
S: X€R
