Respostas

2014-05-14T10:25:17-03:00
A) x^2-4x=5 \\ x^2-4x-5=0

Δ = (- 4)² - 4 . 1 . (- 5)
Δ = 16 + 20
Δ = 36

X = \frac{-(-4)+- \sqrt{36} }{2.1}  \\  \\ X =  \frac{4+-6}{2}

x' =  \frac{4+6}{2} =  \frac{10}{2} = 5                          x" =  \frac{4-6}{2} =  \frac{- 2}{2} = - 1

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