Question

achar as raizes das equações
$x ^{2} - x - 20 = 0$

Answer 1

${x}^{2} - x - 20 = 0 \\ \\ delta = 1 + 80 = 81 \\ \\ x = \frac{1 + \sqrt{81} }{2} = \frac{1 + 9}{2} = \frac{10}{2} = 5\\ \\ x = \frac{ 1 - \sqrt{81} }{2} = \frac{1 - 9}{2} = \frac{ - 8}{2} = - 4$

As raízes são -4 e 5.

Answer 2

x^2 - x - 20= 0
a = 1; b = - 1; c = - 20
∆= b^2-4ac
∆= (-1)^2-4.1.(-20)
∆ = 1 + 80
∆ = 81
x = [- b +/- √∆]/2a
x = [-(-1) +/- √81]/2.1
x' = [1 + 9]/2 = 10/2 = 5
x" = [1-9]/2 = -8/2 = - 4

R. { - 4 ; 5}