Question

Resolva as equações do 2°grau,com a formula de Bhaskara.
a)$x^{2} -7x-8=0$

b)$x^{2} -5x-36=0$

Answer 1

x² - 7x - 8 = 0
a = 1; b = - 7; c = - 8

Δ = b² - 4ac
Δ = (-7)² - 4.1.(-8)
Δ = 49 + 32
Δ = 81

x = - b +/- √Δ = - ( - 7) +/- √81
         2a                  2.1

x =  7 + 9 = 16/2 = 8 
          2

x = 7 - 9 = - 2/2 = - 1
        2

R.: x = 8 e x = - 1

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b)
x² - 5x - 36 = 0

a = 1; b = - 5; c = - 36

Δ = b² - 4ac
Δ = (-5)² - 4.1.(-36)
Δ = 25 + 4.36
Δ = 25 + 144
Δ = 169

x = - b +/- √Δ = - ( - 5) +/- √169  
          2a                     2.1

x = 5 + 13 = 18/2 = 9
         2

x = 5 - 13 = - 8/2 = - 4
        2

R.: x = 9 e x = - 4