Question

calcule as raizes das equaçoes: a) x-x-20

Answer 1

x² - x - 20 = 0
a = 1; b = - 1; c = - 20

Δ = b² - 4ac
Δ = (-1)² - 4.1.(-20)
Δ = 1 + 4.20
Δ = 1 + 80
Δ = 81

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

x = - b +/- √Δ       - (-1) +/- √81
      -------------  =  ------------------
             2a                  2.1

x = 1 + 9
      ------- = 10/2 = 5
         2

x = 1 - 9
     -------  =  - 8/2 = - 4
        2

R.: x = 5 e  x = - 4