Resposta:
a) x² - 25 = 0, sendo U = {-5, -2,0, 2,5).
[tex](-b±\sqrt{b²-4.a.c})/2.a[/tex]
[tex](0±\sqrt{0²- 4.1.(-25)})/2.1[/tex]
[tex](0±\sqrt{100})/2[/tex]
[tex](0±10)/2[/tex]
x1=-10/2 = -5
x2=10/2 = 5
b) x² + 3x = 0, sendo U = {-9, -3,0,3,9}.
[tex](-b±\sqrt{b²-4.a.c})/2.a[/tex]
[tex](-3±\sqrt{3²-4.1.0})/2.1[/tex]
[tex](-3±\sqrt{9})/2.[/tex]
[tex](-3±3)/2[/tex]
x1=(3+3)/2=6/2 = 3
x2=(3-3)/2=0/2 = 0
c) x² + 3x - 4 = 0, sendo U = {-4, -1,0, 1,4}.
[tex](-b±\sqrt{b²-4.a.c})/2.a[/tex]
[tex](-3±\sqrt{3²-4.1.(-4)})/2.1[/tex]
[tex](-3±\sqrt{9+16})/2[/tex]
[tex](-3±\sqrt{25})/2[/tex]
[tex](-3±5)/2[/tex]
x1=(-3+5)/2 = 2/2 = 1
x2=(-3-5)/2 = -8/2 = -4
d) x² – 2x = 3, sendo U = {-3, -1,0, 1,3}.
x² - 2x - 3 = 0
[tex](-b±\sqrt{b²-4.a.c})/2.a[/tex]
[tex](-(-2)±\sqrt{(-2)²-4.1.(-3)})/2.a[/tex]
[tex](2±\sqrt{(4+12})/2[/tex]
[tex](2±\sqrt{16})/2[/tex]
[tex](2±4)/2[/tex]
x1 = (2+4)/2 = 6/2 = 3
x2 = (2-4)/2 = -2/2 = -1
