Question

ache a raiz da equação x²-x-20

Answer 1

X²-x-20 = 0
Δ = b²-4ac
Δ = (-1)² - 4.1.(-20)
Δ = 1+80
Δ = 81
x = (-b+/-\/Δ)/2a
x = (-(-1)+/-\/81)/2
x = (1+/-9)/2
x' = (1+9)/2 --> x' = 10/2 --> x' = 5
x" = (1-9)/2 --> x" = -8/2 --> x" = -4
S: {5;-4}

Answer 2

Olá, bom dia ☺

Resolução:

x² - x - 20 = 0

Coeficientes:

a=1
b= -1
c= -20

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

Valores de x:

$\\x= \frac{-b\pm \sqrt{\Delta} }{2.a} \\ \\ x= \frac{-(-1)\pm \sqrt{81} }{2} \\ \\ x= \frac{1\pm9}{2} \\ \\ x'= \frac{1+9}{2}= \frac{10}{2} =5 \\ \\ x''= \frac{1-9}{2} = \frac{-8}{2} =-4$

Bons estudos :)