Question

a) x² - 5 + 6 = 0
b) x² -8x + 12 = 0
c) x² + 2x - 8 = 0
d x² - 5x + 8 = 0

Answer 1

a) x² - 5x + 6 = 0
(x - 3)(x - 2) = 0
x - 3 = 0 ---> x' = 3
x - 2 = 0 ---> x'' = 2

S = { 2 ; 3 }



b) x² - 8x + 12 = 0
(x - 6)(x - 2) = 0
x - 6 = 0 ---> x' = 6
x - 2 = 0 ---> x'' = 2

S = { 2 ; 6 }



c) x² + 2x - 8 = 0  
(x - 2)(x + 4) = 0
x - 2 = 0 ---> x' = 2
x + 4 = 0 ---> x'' = - 4

S = { - 4 ; 2 }



d) x² - 5x + 8 = 0
Δ = b² - 4ac ---> Δ = (-5)² - 4.1.8 ---> Δ = 25 - 32 ---> Δ = - 7 

Não existe raiz real, pois Δ<0.