Question

a funcao real f , de variavel real , dada por f(x) = -x²+12x +20

Answer 1

f(x) = - x² + 12x + 20
0 = - x² + 12x + 20
- x² + 12x + 20 = 0
a = - 1; b = 12; c = 20

Δ = b² - 4ac
Δ = 12² - 4.(-1).20
Δ = 144 + 4.20
Δ = 144 + 80
Δ = 224

x = - b +/- √Δ = - 12 +/- √224
          2a                 2.(-1)

x' = - 12 + 4√14 = 6 - 2√14
            - 2

x" = - 12 - 4√14 = 6 + 2√14
           - 2

Resposta: x' = 6 + 2√14 e x" = 6 - 2√14
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224: 2
112: 2
56: 2
28: 2
14: 2
7: 7
1     =  2.2.2.2.2.7 = 16.14 = √16.√14 = 4√14