Question

encontre as raizes das equaçoes x2 - x - 20 = 0

Answer 1

$x^2-x-20=0\\\\a=1,\ b=-1,\ c=-20\\\\ \Delta=b^2-4.a.c\\\\ \Delta=(-1)^2-4.1.(-20)\\ \Delta=1+80\\ \Delta=81$

$x= \dfrac{-b \pm \sqrt{\Delta} }{2.a}\\\\\\x= \dfrac{1 \pm 9}{2} \\\\\\x'=5,\ x''=-4$

Forte abraço!

Answer 2

Vamos lá :

x² - x - 20 = 0

a = 1 ; b = - 1 ; c = - 20

Δ = b² - 4ac
Δ = (-1)² - 4.1.(-20)
Δ = +1 + 80
Δ  = + 81      ⇒⇒√Δ = 9

Bhaskara :

x = - b ± √Δ / 2a
x = -(- 1) ± 9/2.1
x = + 1 ± 9/2

x' = +1 + 9/2 = 10/2 = 5
x'' = +1 - 9/2 = - 8/2 = - 4

S = {- 4,5}

Espero ter ajudado !!!