Question

Achar as raizes das equaçoes
X2-x-20=0

Answer 1

x² -x - 20 = 0

a = 1
b = -1
c = -20

Δ = b² -4 . a . c

Δ = (-1)² -4 . 1 . (-20)
Δ = 1 + 80
Δ = 81

-b +- √Δ   / 2 . a
-(-1) +- √ 81  /  2 . 1
1 +- 9  / 2

x' = 1 + 9 / 2
x' = 10/2
x' = 5

x" = 1 - 9  / 2
x" = -8  /2
x" = -4

Resposta : S{ 5 e  -4 }