Question

Resolvendo a equação do 2° grau x² – x – 20 = 0, teremos a seguinte solução: *

Answer 1

Resposta:

x = {5, -4}

Explicação passo-a-passo:

Resolvemos x² – x – 20 = 0 usando a fórmula de Bhaskara -b+-Vb²-4ac / 2a

-(-1)+-V-1²-4.1.-20 / 2.1

1 +- V1+80 / 2

1 +- V81 / 2

1 +- 9 / 2

x' = 1 + 9 / 2

x' = 10/2

x' = 5

x'' = 1 - 9 / 2

x'' = -8/2

x'' = -4

Answer 2

$\boxed{\begin{array}{lr} x^2-x-20=0 \end{array}}$

a = 1

b = -1

c = -20

$\boxed{\begin{array}{lr} \Delta=b^2-4.a.c\\\Delta=(-1)^2-4.1.-20\\\Delta=1+80\\\Delta=81 \end{array}}$

$x=\dfrac{-b\pm\sqrt{\Delta}}{2.1}\\\\\\x=\dfrac{1\pm9}{2}\\\\\\x'=\dfrac{1+9}{2}\\\\\\x'=\dfrac{10}{2}\\\\\\x'=5\\\\\\x''=\dfrac{1-9}{2}\\\\\\x''=\dfrac{-8}{2}\\\\\\x''=-4$

$S=\{5\ ,\ -4\}$