Question

Encontre as raizes das equações x2-8x+7=0

Answer 1

Olá ! 

Resolvendo ... 

x² - 8x + 7 = 0 

Δ = 64 - 28 

Δ = 36 

x = (8 +- √36)/2 

x = (8 +- 6)/2 

x' = 14/2 

x' = 7 

x'' = 2/2

x'' = 1                                  S = { 1 , 7 }                                  ok 

Answer 2

x² - 8x + 7 = 0

a = 1
b = -8
c = 7

Δ = b² -4 .a . c 
Δ = (-8)² -4 . 1 . 7
Δ = 64 - 28
Δ = 36

$\mathtt{\dfrac{-b+-~\sqrt{\Delta}}{2~.~a}~~=~~\dfrac{-(-8)+-~\sqrt{36}}{2~.~1}~~=~~\dfrac{8+-~6}{2}} \\ \\ \\ \mathtt{x'=\dfrac{8+6}{2}~~=~~\dfrac{14}{2}~~=~~7} \\ \\ \\ \mathtt{x'' = \dfrac{8 - 6}{2}~~=~~\dfrac{2}{2}~~=~~1} \\ \\ \\ \boxed{\boxed{\mathtt{Resposta: S:~~1~~~e~~~7}}}$