Question

menos x ao quadrado + 6x - 5 = 0

Answer 1

-x² + 6x - 5 = 0

a = -1
b = 6
c = -5

Δ = b² -4 .a . c
Δ = 6² -4 . (-1) . (-5)
Δ = 36 + 4 . (-5)
Δ = 36 - 20
Δ = 16

$\mathtt{\dfrac{-b+-~\sqrt{\Delta}}{2~.~a}}~~=~~\dfrac{-6+-~\sqrt{16}}{2~.~(-1)}~~=~~\dfrac{-6+-~4}{-2}} \\ \\ \\ \mathtt{x' = \dfrac{-6+4}{-2}~~=~~\dfrac{-2}{-2}~~=~~1} \\ \\ \\ \mathtt{x'' = \dfrac{-6-4}{-2}~~=~~\dfrac{-10}{-2}~~=~~5} \\ \\ \\ \boxed{\boxed{\mathtt{Ressposta: S\{1~~e~~5\}}}}$